zstd 1.3.4

• Remove mallocs from Compress/Decompress (#31)
• update zstd to 1.3.4 (#18)
• get rid of static error code translation and use C call (#29)
• reduce memory allocations in Reader (#20)

zstd 1.3.0

update zstd to 1.3.0 (#18)

zstd 0.5.0

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

match zlib library interface and documentation where appliccable