HNotate

Copperbox revision 233.

I've changed the score datatypes so they can be Functor instances (and Foldable and Traversable instances). They should really have been in this form in the first place (ah hindsight!), but I had wanted to make duration handling easier for chords and graces and had the datatypes parametrized with two holes - glyph and duration, rather than just glyph.