Zstandard v1.3.1

• New license : BSD + GPLv2
• perf: substantially decreased memory usage in Multi-threading mode, thanks to reports by Tino Reichardt (@mcmilk)
• perf: Multi-threading supports up to 256 threads. Cap at 256 when more are requested (#760)
• cli : improved and fixed --list command, by @ib (#772)
• cli : command -vV lists supported formats, by @ib (#771)
• build : fixed binary variants, reported by @svenha (#788)
• build : fix Visual compilation for non x86/x64 targets, reported by @GregSlazinski (#718)
• API exp : breaking change : ZSTD_getframeHeader() provides more information
• API exp : breaking change : pinned down values of error codes
• doc : fixed huffman example, by Ulrich Kunitz (@ulikunitz)
• new : contrib/adaptive-compression, I/O driven compression level, by Paul Cruz (@paulcruz74)
• new : contrib/long_distance_matching, statistics tool by Stella Lau (@stellamplau)
• updated : contrib/linux-kernel, by Nick Terrell (@terrelln)