2.8.2

1. Only show multi-disc icon, and prompt for disc to use, etc., if LMS is set to group multi-disc albums.
2. Add add and play actions to subtoolbar for 'All songs' listings.
3. Don't show disc headers in 'All songs' listings.
4. Hide settings password.
5. Update gallery image when track changes if this is showing now playing cover.
6. Only show 'Play disc starting at track' if there are multiple discs.