Interfaces: removed VFS crap.
Util: documented ShortcutManager.
Interfaces: documented IAlbumArtProvider.
Interfaces: documented IArtistBioFetcher.
Interfaces: added IAudioSearchRequest::error().
Interfaces: documented IAudioPile and IAudioScrobbler.
Interfaces: documented AudioStructs.
Util: fixed docs for BackendSelector and CustomCookeJar.