[Open Assets] Character Super Themes 1.2

+ Added support for mods to add their own entries to the superTheme and specialTheme tables.
* Super themes no longer appear as empty themes in the sound test. Turns out I didn't understand what should and what shouldn't be freeslotted.

* Bugfix: Fixes issue with characters without set Super themes.

+ Characters can have more than one Super theme; on spawn and skin change, a random Super theme of theirs is chosen to play when Super
* Slightly changed which Super themes play for which characters (mostly adding a few themes)
* Super themes no longer play over boss themes
+ Added setsupertheme command. Allows setting a specific theme to always play when Super. Run it without parameters to see usage (and to unset having a specific theme always play)
* Attempted to rebalance audio levels
* Switched out Stardust Speedway Bad Future to Zummone's alternate loop interpretation.