3.1.4

Enhancements:

• detect "used" variables in build.sh, bld.bat and any output scripts, in
  addition to what already existed in meta.yaml. Used variables end up in the
  hash. #2576
• don't merge build and host prefixes. We used to do this when host subdir ==
  build subdir. Keep them separate, so that build tools in build prefix won't
  ever interfere with software installed to host, to be packaged. #2579

Bug fixes:

• exclude grouped keys from zip_keys when computing hashes. Only direct dependencies affect the hash. #2573
• fix always_include_files usage omitting other ordinarily installed files #2580

Contributors:

• @msarahan