[devel] Mentioned in the documentation that applications must #include "zlib.h"

if they need access to anything in zlib.h, and that a number of
macros such as png_memset() are no longer accessible by applications.
diff --git a/CHANGES b/CHANGES
index 1381acd..f9e607b 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3158,8 +3158,11 @@
 Version 1.5.1beta03 [January 14, 2011]
   Fixed typecasting of some png_debug() statements (Cosmin)
 
-Version 1.5.1beta04 [January 15, 2011]
+Version 1.5.1beta04 [January 16, 2011]
   Updated documentation of png_set|get_tRNS() (Thomas Klausner).
+  Mentioned in the documentation that applications must #include "zlib.h"
+    if they need access to anything in zlib.h, and that a number of
+    macros such as png_memset() are no longer accessible by applications.
 
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