cunit: Remove scope blocks from CU_ASSERT & co macros
png: Add png.bi wrapper for the version-specific png headers
Add simple tests to ensure that .bi files compile ok
png: Fix forward typedefs
zlib: Remove #include sys/types.bi, not needed
tests: Add zlib
png: Remove unnecessary #includes
makefile: Add png target
raw: png: Remove more internal #defines, preserve non-internal ones
Merge branch 'raw'

Conflicts:
	inc/png12.bi
	inc/png14.bi
	inc/png15.bi
	inc/png16.bi
	makefile
png: Fix png_sizeof()
png12: Fix png_info_init macro
png: Fix png_composite macros
raw: libpng 1.2.51, 1.4.13, 1.5.19, 1.6.14
Merge branch 'raw'
tests: Compile to *.asm only, don't even assemble to *.o
zlib: Remove gzgetc macro

There still is the gzgetc function (and also the gzgetc_ wrapper) which
can be used instead. In the original zlib.h, gzgetc is redefined as a macro
"for speed", but I don't think it's worth it to translate it to FB.

Translating it to FB would in fact not be trivial due to the use of -- and
++ operators. The only way to translate it would be as a private function,
and at that point we may aswell use the original gzgetc function from zlib.
zlib: Add #inclib "z"
zlib: Remove unnecessary #includes
makefile: Add "zlib" to "all" too