Neume

Copperbox revision 1423.

I've started a new fork of Neume with modified data types for the syntax - 2L_Neume. In one place I'm using two-level types, though the instance is simplistic and might not be worth it - when I started out I was expecting to use two level types more but there actually isn't much recursion in Neume's syntax. In other places I've unified the syntax which definitely seems worthwhile.

I'm also looking to avoid some of the wildness in the previous revision (tri-functors, StateMap) and use more prosaic coding techniques.