refactored the caching mechanism to use AppDirs.user_cache_dir instead of <cwd>/__lingpy__ as cache dir
small fix in setup py where important files were missing, also added pathlib as requirement for py < 3.4
didn't look at the code, was struck by travis error
trying to fix installation bug on travis
last try to fix bug in install with missing modules
new approach to caching: pickle the whole object and make unpickling explicit.
Merge remote-tracking branch 'upstream/master'
cheap workaround for installation problems
modify sound-class models, data now stored in cache