Neume

Copperbox revision 1230.

I've fixed the bug where LilyPond was getting relative pitch transformations wrong with overlays. This means that the Overlay1 example is now printing correctly for both ABC and LilyPond...

Unfortunately just to get output the code has become horrible and ad hoc - I think this version of the repository it going to be a high water mark (or cynically a low water mark) for Neume, as I'm going to have to devise a better way of creating and processing scores - i.e. note lists that might be overlayed, repeated etc.