Add Seasonal backgrounds
Fix HUD test having out of date value
Add momentary HUD toggle
Change shift-tab to cycle between available HUD visibility modes
Ensure virtual track time is long enough for test beatmaps
Only play results panel animation once (and only for the local user)
Probably wouldn't be used anyway.
When there isn't a seasonal event, we don't want to fall back to the basic background here, but rather to the user selected background source.