FEA: load playlists from favourite playlist lisr

[marcogrecopriolo]

As the it is, the playlists tab is not very useful: I have to have all of my playlists open if I want to switch from one playlist to another. Would be very useful if there was an open playlist option, so that I could choose one from the favourites, or at least the playlist selector listed all of the open playlists plus all of the favourite playlists.