Remove the "last changed" version information from source comments

This information is maintained by the version control system.
diff --git a/example.c b/example.c
index 34ecfde..412affd 100644
--- a/example.c
+++ b/example.c
@@ -2,11 +2,12 @@
 #if 0 /* in case someone actually tries to compile this */
 
 /* example.c - an example of using libpng
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ *
  * Maintained 2018 Cosmin Truta
  * Maintained 1998-2016 Glenn Randers-Pehrson
- * Maintained 1996, 1997 Andreas Dilger)
- * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Maintained 1996-1997 Andreas Dilger
+ * Written 1995-1996 Guy Eric Schalnat, Group 42, Inc.
+ *
  * To the extent possible under law, the authors have waived
  * all copyright and related or neighboring rights to this file.
  * This work is published from: United States, Canada.
diff --git a/png.c b/png.c
index 4be4f9f..1e7003c 100644
--- a/png.c
+++ b/png.c
@@ -814,7 +814,6 @@
 #ifdef PNG_STRING_COPYRIGHT
    return PNG_STRING_COPYRIGHT
 #else
-#  ifdef __STDC__
    return PNG_STRING_NEWLINE \
       "libpng version 1.6.36.git" PNG_STRING_NEWLINE \
       "Copyright (c) 2018 Cosmin Truta" PNG_STRING_NEWLINE \
@@ -823,13 +822,6 @@
       "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
       "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
       PNG_STRING_NEWLINE;
-#  else
-   return "libpng version 1.6.36.git\
-      Copyright (c) 2018 Cosmin Truta\
-      Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson\
-      Copyright (c) 1996-1997 Andreas Dilger\
-      Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
-#  endif
 #endif
 }
 
diff --git a/pngdebug.h b/pngdebug.h
index 15a7ed0..00d5a45 100644
--- a/pngdebug.h
+++ b/pngdebug.h
@@ -1,10 +1,10 @@
 
 /* pngdebug.h - Debugging macros for libpng, also used in pngtest.c
  *
- * Last changed in libpng 1.6.8 [December 19, 2013]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2013 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngerror.c b/pngerror.c
index ad48bfb..df32380 100644
--- a/pngerror.c
+++ b/pngerror.c
@@ -1,10 +1,10 @@
 
 /* pngerror.c - stub functions for i/o and memory allocation
  *
- * Last changed in libpng 1.6.31 [July 27, 2017]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngget.c b/pngget.c
index 2325508..5abf1ef 100644
--- a/pngget.c
+++ b/pngget.c
@@ -1,10 +1,10 @@
 
 /* pngget.c - retrieval of values from info struct
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pnginfo.h b/pnginfo.h
index 2fcf868..1f98ded 100644
--- a/pnginfo.h
+++ b/pnginfo.h
@@ -1,10 +1,10 @@
 
 /* pnginfo.h - header file for PNG reference library
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2013,2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngmem.c b/pngmem.c
index ff3ef7e..09ed9c1 100644
--- a/pngmem.c
+++ b/pngmem.c
@@ -1,10 +1,10 @@
 
 /* pngmem.c - stub functions for memory allocation
  *
- * Last changed in libpng 1.6.26 [October 20, 2016]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngpread.c b/pngpread.c
index c4ba51c..fd0f0b2 100644
--- a/pngpread.c
+++ b/pngpread.c
@@ -1,10 +1,10 @@
 
 /* pngpread.c - read a png file in push mode
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngpriv.h b/pngpriv.h
index b9187fd..acaf15c 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -1,10 +1,10 @@
 
 /* pngpriv.h - private declarations for use inside libpng
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngread.c b/pngread.c
index bff7503..2d3a100 100644
--- a/pngread.c
+++ b/pngread.c
@@ -1,10 +1,10 @@
 
 /* pngread.c - read a PNG file
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngrio.c b/pngrio.c
index 3722214..7946358 100644
--- a/pngrio.c
+++ b/pngrio.c
@@ -1,10 +1,10 @@
 
 /* pngrio.c - functions for data input
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2016,2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngrtran.c b/pngrtran.c
index 67d1f24..3302a7c 100644
--- a/pngrtran.c
+++ b/pngrtran.c
@@ -1,10 +1,10 @@
 
 /* pngrtran.c - transforms the data in a row for PNG readers
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngrutil.c b/pngrutil.c
index 7001f19..9056712 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,10 +1,10 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngset.c b/pngset.c
index 7cf54d9..e90e35a 100644
--- a/pngset.c
+++ b/pngset.c
@@ -1,10 +1,10 @@
 
 /* pngset.c - storage of image information into info struct
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngstruct.h b/pngstruct.h
index 699e8ac..d576031 100644
--- a/pngstruct.h
+++ b/pngstruct.h
@@ -1,10 +1,10 @@
 
 /* pngstruct.h - header file for PNG reference library
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngtrans.c b/pngtrans.c
index de84aa6..97586c0 100644
--- a/pngtrans.c
+++ b/pngtrans.c
@@ -1,10 +1,10 @@
 
 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngwio.c b/pngwio.c
index e539168..10e919d 100644
--- a/pngwio.c
+++ b/pngwio.c
@@ -1,10 +1,10 @@
 
 /* pngwio.c - functions for data output
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2014,2016,2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngwrite.c b/pngwrite.c
index 5bd87f3..8329473 100644
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -1,10 +1,10 @@
 
 /* pngwrite.c - general routines to write a PNG file
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngwtran.c b/pngwtran.c
index 3a1e0a2..9ed551e 100644
--- a/pngwtran.c
+++ b/pngwtran.c
@@ -1,10 +1,10 @@
 
 /* pngwtran.c - transforms the data in a row for PNG writers
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2016,2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/pngwutil.c b/pngwutil.c
index ab431e7..562ea8f 100644
--- a/pngwutil.c
+++ b/pngwutil.c
@@ -1,10 +1,10 @@
 
 /* pngwutil.c - utilities to write a PNG file
  *
- * Last changed in libpng 1.6.35 [July 15, 2018]
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer