These are things I want to see get done, and may or may not get around to.

BUGS:
 * During-gameplay judgement display (perfect, great, etc.) isn't updating
   correctly. The animations are correct, but it's not using the right
   graphics, instead cycling seemingly randomly between Marvellous and
   Perfect.

 * In the music select, the groove radar is stuck at max everything.

 * In jukebox mode, scores aren't reset between songs. This means the score
   meter goes insanely high and eventually (if allowed to go on for long
   enough) an assert fails due to an integer overflow.

 * Texture/etc loading can't handle redirects that start with the file name of
   the file they refer to (e.g. "Foo Bar.redir" referring to "Foo"); it instead
   just goes into an infinite loop repeatedly resolving to the redirect.

Other:
 * We need redirects for the note color NoteSkin elements, e.g. Tap Note 12th,
   etc. I've added some to the common fallbacks, but dance could use some too.

 * Redesign ScreenSelectMusic to make the layout much much more freeform. We
   could have all our music selection needs in one program just by setting up
   banner and/or custom graphic as a WheelItem element and allowing more
   customization of the wheel "path". That should be sufficient for everything
   I can think of except for style changes in 2nd generation PiU song wheel.

 * Allow themes to specify left/right vs. up/down item selection controls on a
   per-screen basis. The best way to do this would be to separate
   MenuLeft / MenuRight from PrevItem / NextItem and mapping the latter two
   appropriately inside ScreenSelect.