version 0.1.23

* split up into multiple files

* unburdened data provider classes
* use mbrainz api directly without depending on musicbrainzngs anymore
* set useragent in request header, makes discogs requests work again
* limit request rate for all dataproviders

* replaced Album class with BunchOfTracks and Track classes
* improved folder, track and metadata handling
* understand artist as track based
* set artist as albumartist if appropriate
* use albumartist for BunchOfTracks artist searches

* use json instead of pickle for saving the cache (delete your cachefile)
* removed cache save interval config option (hardcoded to 10min)
* use logging for verbose output
* other code rewrites, refactors and improvements

(finally a new version <3)