c++: Switch to c++ headers

[clang-tidy]Found with hicpp-deprecated-headers

Signed-off-by: Rosen Penev <rosenp@gmail.com>
diff --git a/src/Array.cpp b/src/Array.cpp
index f6e1297..22c254b 100644
--- a/src/Array.cpp
+++ b/src/Array.cpp
@@ -18,11 +18,11 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
 #include <plist/Array.h>
 
 #include <algorithm>
-#include <limits.h>
+#include <climits>
+#include <cstdlib>
 
 namespace PList
 {
diff --git a/src/Boolean.cpp b/src/Boolean.cpp
index 35f2a57..9f14904 100644
--- a/src/Boolean.cpp
+++ b/src/Boolean.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <plist/Boolean.h>
 
 namespace PList
diff --git a/src/Data.cpp b/src/Data.cpp
index 11439d3..89b4f4e 100644
--- a/src/Data.cpp
+++ b/src/Data.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <plist/Data.h>
 
 namespace PList
diff --git a/src/Date.cpp b/src/Date.cpp
index 87e8a50..a3c8592 100644
--- a/src/Date.cpp
+++ b/src/Date.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <plist/Date.h>
 
 namespace PList
diff --git a/src/Dictionary.cpp b/src/Dictionary.cpp
index cc4626b..6da0eee 100644
--- a/src/Dictionary.cpp
+++ b/src/Dictionary.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <plist/Dictionary.h>
 
 namespace PList
diff --git a/src/Integer.cpp b/src/Integer.cpp
index e357f72..d394ee1 100644
--- a/src/Integer.cpp
+++ b/src/Integer.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <plist/Integer.h>
 
 namespace PList
diff --git a/src/Key.cpp b/src/Key.cpp
index 2e92f20..8c96e59 100644
--- a/src/Key.cpp
+++ b/src/Key.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <plist/Key.h>
 
 namespace PList
diff --git a/src/Node.cpp b/src/Node.cpp
index 51ecd75..fb79911 100644
--- a/src/Node.cpp
+++ b/src/Node.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <plist/Node.h>
 #include <plist/Structure.h>
 #include <plist/Dictionary.h>
diff --git a/src/Real.cpp b/src/Real.cpp
index 4587701..3ac67f2 100644
--- a/src/Real.cpp
+++ b/src/Real.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <plist/Real.h>
 
 namespace PList
diff --git a/src/String.cpp b/src/String.cpp
index 7bc3abc..39717c2 100644
--- a/src/String.cpp
+++ b/src/String.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <plist/String.h>
 
 namespace PList
diff --git a/src/Structure.cpp b/src/Structure.cpp
index a06618d..9445c23 100644
--- a/src/Structure.cpp
+++ b/src/Structure.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <plist/Structure.h>
 
 namespace PList
diff --git a/src/Uid.cpp b/src/Uid.cpp
index 6456dce..204cd68 100644
--- a/src/Uid.cpp
+++ b/src/Uid.cpp
@@ -18,7 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <plist/Uid.h>
 
 namespace PList