The changes in 1.2.9 (1.2.10 is just a bug fix release) affecting the use of
zlib in wxWidgets are:
- Improve compress() and uncompress() to support large lengths
- Fix bug when level 0 used with Z_HUFFMAN or Z_RLE
- Fix bugs in creating a very large gzip header
- Dramatically speed up deflation for level 0 (storing)
Closes https://github.com/wxWidgets/wxWidgets/pull/380