Song list sorting

[DolphinDTM]

The song list is a mess. I can't even tell what order the songs appear in, but it's not alphabetical and not alphabetically by folder name.

Basically we need options for sorting:

• Sort by Title
• Sort by Level
• Sort by Artist
• Sort by Difficulty
• Sort by Genre (hi pop'n!!)

there are probably other applicable sorting methods but these are the most important ones that come to mind.

[zardoru]

genre is so wide open i probably would not seriously consider it.

[DolphinDTM]

I didn't really expect you to implement genre sorting anyway