[musicdb] fix for duplicates when mixing musicbrainz & non-musicbrainz artists
[musicdb] don't clean music library on scan (fix for deleting music when source is offline)
[musicdb] clear stale comment
[musicdb] fix the album/artist updaters and allow the scrapers to update artist name & album details. allows users to fix scanning problems more easily.
[musicdb] announce changes when updating artists and albums