Zstandard v1.1.3

cli : zstd can decompress .gz files (can be disabled with make zstd-nogz or make HAVE_ZLIB=0)
cli : new : experimental target make zstdmt, with multi-threading support
cli : new : improved dictionary builder "cover" (experimental), by @terrelln, based on previous work by @ot
cli : new : advanced commands for detailed parameters, by @inikep
cli : fix zstdless on Mac OS-X, by @apjanke
cli : fix #232 "compress non-files"
API : new : lib/compress/ZSTDMT_compress.h multithreading API (experimental)
API : new : ZSTD_create?Dict_byReference(), requested by Bartosz Taudul
API : new : ZDICT_finalizeDictionary()
API : fix : ZSTD_initCStream_usingCDict() properly writes dictID into frame header, by @indygreg (#511)
API : fix : all symbols properly exposed in libzstd, by @terrelln
build : support for Solaris target, by @inikep
doc : clarified specification, by @iburinoc

Sample set for reference dictionary compression benchmark

# Download and expand sample set 
wget https://github.com/facebook/zstd/releases/download/v1.1.3/github_users_sample_set.tar.zst
zstd -d github_users_sample_set.tar.zst
tar xf github_users_sample_set.tar

# benchmark sample set with and without dictionary compression
zstd -b1 -r github
zstd --train -r github
zstd -b1 -r github -D dictionary

# rebuild sample set archive
tar cf github_users_sample_set.tar github
zstd -f --ultra -22 github_users_sample_set.tar