Implement back button in AlbumSlideshow
De-select button after switching slides
Support jumping to track in AlbumSlideshow
Always stop playback of AlbumSlideshow when menuSwap is called
Fix bug in back action and stop AlbumSlideshow playback
Fix bug introduced by track-level AlbumSlideshow indexing (track: null now works again)
Fix bug when leaving AlbumSlideshow on the first slide
Collapse the menuStack when doing a menuSwap (to prevent popping back to the same menu)
Correctly copy and play non-library audio tracks of AlbumSlideshow