Support noise instruments in music packs #325
Description
aka "Bring instrument syntax more into harmony with what AddMusicK and AddMusicKFF and all of their variants/AddMusicY allow"
AddMusicKFF allows replacing the filename for a sample with nXX (replacing XX with a hex number from 0 to 0x1F -- note that there are no quotes around it all) to use the noise generator for audio output instead of a BRR sample. CoilSnake should support this too.
(Documentation will also need to be updated to talk about this syntax, and about how the noise stuff relies on sample 0 being a looping sample in order to get its envelope right.)