HNotate

Copperbox revision 281.

I've put logging around the most important processing functions in HNotate - and added alternative top-level functions outputAbc_debug and outputLilyPond_debug that do the processing with logging on.

The problems I've seen where Trees.hs doesn't produce any output for LilyPond and other examples drop directives (e.g. partial measures) look like they stem from the preprocessing stage producing bad output. To fix...