NDLR start stop messages

[drGrov]

My vote is for proposal 1. I think the NDLR should send a START message the first time something starts, be it a single part or everything, and a STOP when the last thing stops. I don't always kick things off by starting all the parts together, maybe just a pad + drone or single motif so having START/STOP messages in these cases is desirable.

I hadn't realised you could confine the START/STOP messages to a single port. That opens up interesting possibilities...