Mullein

Copperbox revision 579.

I've added LilyPond output code to the Ssf.lhs example from the Haskore-vintage package. Unfortunately there are two problems. Trills generate erroneous output, so I've had to comment them out. Also Mullein wrongly calculates relative pitch, so the score is printed a octave too high.

The second problem has taken more investigation than I would have expected. The only real progress so far is I've changed Mullein to have middle c at C5 to match Haskore. For usability it is no doubt wise for them both to match.