This is a heavily modified and shrinked version of zlib 1.2.3

- Removed comments from zlib.h
- Removed gzip/zip archive I/O
- Removed Compression part
- Removed infback.c
- Added Assimp #idefs to exclude it if not needed
- Disabled debug macros in zutil.h

All inflateNNN functions are available, for the rest you need to try.
If a function is needed but is not there, get zlib and add the 
corresponding files to the repos. zlib is quite clean, it shouldn't
be too difficult to configure it to your needs.