HNotate

Copperbox revision 260.

I've revised the ToNoteList module of HNotate and it now brackets notes into groups when the consecutive durations are less than a quarter - then they can be beamed in the output.

Unfortunately, neither the Abc or LilyPond backends support beaming yet. LilyPond brackets a beam group after the first note so a triplet would be c [e g], whereas HNotate has them [c e g] - clearly a translation would be quite easy for this one. Abc is more tricky - beaming is indicated by the absence of a space separator between notes. To get this right I will probably have to change the Abc pretty print combinators.