Merge branch 'dev'

Merge pull request facebook#531 from facebook/dev

Zstandard v1.1.3

updated manual

minor display improvement in fuzzer when nb of tests is very large

updated NEWS

Merge pull request facebook#311 from Cyan4973/dev

Dev

Merge pull request facebook#295 from Cyan4973/dev

v0.8.1

Merge pull request facebook#274 from inikep/dev06

legacy decoders v0.7 and v0.8

Merge pull request facebook#268 from Cyan4973/dev

v0.8.0

Merge pull request facebook#270 from inikep/dev07

decoder for v0.8