lirio

Copperbox revision 2789.

I've reworked the note lists to use more overloading and changed their internals so they wrap one of two primitive note lists - one for relative duration and the other for absolute duration. By wrapping one of these, note lists can get most of their type class instances from lifting the appropriate operations on the primitive note list, usually only NoteM and ChordM need implementing "longhand".

Quite a bit of code still needs tidying up...