Remove orphan tracks from playlists after they are removed from library

model/album.go

@@ -46,6 +46,5 @@ type AlbumRepository interface {
 	GetStarred(options ...QueryOptions) (Albums, error)
 	Search(q string, offset int, size int) (Albums, error)
 	Refresh(ids ...string) error
-	PurgeEmpty() error
 	AnnotatedRepository
 }

model/artist.go

@@ -36,6 +36,5 @@ type ArtistRepository interface {
 	Search(q string, offset int, size int) (Artists, error)
 	Refresh(ids ...string) error
 	GetIndex() (ArtistIndexes, error)
-	PurgeEmpty() error
 	AnnotatedRepository
 }