Support for 1/2/4-bit palettized PNG
Unpack 1/2/4 bpp into 8 bpp scanline buffer + support grayscale 1/2/4 bpp
Fix for interlaced and small images + cleanup
Removing tabs and using 3-spaces indents to match local coding style
Documentation
stb_image: Trivial optimizations for filter path when img_n==out_n.
stb_image: Add 'static' for some internal funcs, STBIDEF for external ones.
stb_image: Keep zout in a local var during stbi__parse_huffman_block.
stb_image: Fast path for matches with dist=1 (runs) in stbi__parse_huffman_block.
stb_image: Extract zhuffman_decode slow path into own function.
stb_image: Make 'fast' table contain code size and value directly.
stb_image: Guess decoded image size before zlib decode to avoid unnecessary reallocs.
Merge branch 'master' of https://github.com/ocornut/stb into working
fix incorrect img_n variable for interlaced files, caused files to be totally incorrect if forcing channel count
test program now verifies pngsuite tests against refererence versions
fix 1/2/4-bit png to filter bytes before decoding to pixels;
rename pngsuite/part1 to pngsuite/primary;
check in pngsuite
Merge branch 'optimize' of https://github.com/rygorous/stb into working

Conflicts:
	stb_image.h

Also disable VC6 automatic precompiled headers which were enabled in some projects.
update stb_image version & changelog
Fix assert() that should be STBI_ASSERT()