Add jump list to allow easy browsing to a specific letter in large music collections

[ma261065]

My music collection is pretty huge, and browsing it in a single list is painful. If I want to find an artist starting with (say) "W", I have to scroll for absolutely ages. It would be great if there was a letter divider between each group of artists/albums etc that when tapped brought up the full alphabet in an overlay or something, and then would let you tap any letter to quickly jump to that section.