Merge branch 'dev' into buck

* dev:
  updated NEWS
  fixed MSAN warnings in legacy decoders
  Fix cmake build
  updated NEWS
  Edits as per comments, and change wildcard 'X' to '?'
  Fix Visual Studios project
  Fix pool.c threading.h import
  Fix zstdmt_compress.h include
  Fixed commented issues
  Updated format specification to be easier to understand
  improved #232 fix
  Fixed https://github.com/facebook/zstd/issues/232
  .travis.yml: different tests for "master" branch
  .travis.yml: optimized order of short tests
  .travis.yml: test jobs 12-15
  JOB_NUMBER -eq 9
  improved ZSTD_compressBlock_opt_extDict_generic