Merge pull request DataDog#31 from valyala/remove-mallocs-from-compre…

…ss-decompress

Remove mallocs from Compress/Decompress

Merge pull request DataDog#18 from DataDog/elijah/1.3.0

Update zstd to 1.3.0

Merge pull request DataDog#2 from DataDog/jason/zlib-conformity

match zlib library interface and documentation where appliccable