This was one huge mess where nothing fit together.
Also added an enhancement that the CD Audio boss theme tracks are also played when CD music is generally off, because these have no equivalent in MIDI. This needs to be checked if it's stylistically ok, though.
Since the code is extremely volatile I changed the setup so that the save is a zip file with the regular snapshot plus all added data as separate entries.
This allows compressing everything properly without savegame breaking interference.
Blood does not yet load its savegames, need to check.