Mullein

Copperbox revision 595.

I'm now reasonably happy with Mullein's functionality. I can generate 'good' LilyPond for simple Haskore scores, which at various times I thought would be all but impossible. 'Good' in this context means the output resembles LilyPond that might have been handwritten, it is quite possible that there are still some bugs in the output rendering.

Also, as developing Mullein and its predecessor Haskore has been so long winded, I've got no energy at present to consider writing a Haskore-like score language that is closer to LilyPond and ABC than MIDI. So I've decided to package up Mullein as a Haskore post-processor. This revision is the first step towards that - I've put both Mullein and MulleinHaskore in the same source package. The next round of work will be giving the modules proper interfaces that export only the public functions.