Add IDatabaseExtensions, GetSingle extension method
Add IDatabaseExtensions to compile
GetSingle -> AlbumArtist
GetSingle -> Album
GetSingle -> Art
GetSingle -> Artist
GetSingle -> Favorite
GetSingle -> Folder
GetSingle -> Genre
GetSingle -> Playlist
GetSingle -> Session
GetSingle -> Song
GetSingle -> Video
Generate blank instance, not null if not found
Add IDatabase GetList extension method
GetList -> AlbumArtist
GetList -> Album
GetList -> Artist
GetList -> Favorite
GetList -> Folder