Payasan

I've added rudimentary MIDI output to Payasan.

The implementation is hacked together from code in the initial version of Payasan, at some point I'd like to be able to have notes with individual velocity control and also to represent swing / quantization, so I'm not too unhappy that this code is quite rough (it will be replaced).

That said I suspect it has some errors as the demo "tune" isn't in the register I expect.