threading finished
FEATURE: add ui
FEATURE: add drop tree controller
FEATURE: new ui
FEATURE: result_tree_controller
FEATURE:add thumb_ahnlder
BUGFIX: add type to release
...
FEATURE: start to use musicbrainz
FEATURE: add musicbrainz search
FEATURE: tracklist request
FEATURE: add discogs request and parser
FEATURE: discogs api search
FEATURE: add discogs thumb loader
FEATURE: add scheduler
FEATURE: request_handler