Conflicts:
	stb_image_write.h

to avoid probelm with clang -O2 to outputting buggy code

This reverts commit 9dfa8c7f.

This fixes the error in bug report #516. This should work as intended
since the function definitions line up.

This is 3 short fixes for the file test_truetype.c.

1. Fix the Visual Studio Secure CRT Errors by defining
 _CRT_SECURE_NO_WARNINGS

2. Fix signed/unsigned Character conversion warning/error.

3. Fix the Definitions for the Image packer.
This now works as intended generating usable png files.

Fixes #404

My clang doesn't like the macro defined this way, choking at the callsite on line 195 with "too many arguments provided to function-like macro invocation"

This change matches what is done for STBTT_memset in stb_truetype.h