Mullein

Copperbox revision 555.

Scores are now built with monadic syntax. This allows different motifs to share properties (e.g key and meter) that they inherit from their parent tune.

On a positive note, although the code needs some polishing, Mullein is capable of generating good quality Abc (that's to say output that looks like it might have been hand written), whilst having a fairly simple implementation and a comprehensible interface. This is a significant improvement on HNotate where the code quickly sky-rocketed into ultra-complexity.

Mullein's main deficit is it cannot generate exotic LilyPond (percussion notation, plain song) that HNotate can.