HNotate

Copperbox revision 363.

I've fixed a bug where tuplets were getting assigned zero_duration if they had the same total duration as the preceding note. LilyPond uses a scheme where if a note has the same duration as the last one then the duration can be omitted - HNotate can normally use this, but because triplets have synthesized durations it was causing problems. Now tuplets always print the unit duration with the first member tuplet.