Analogue-sequencer

I tracked down the cause of the sync loss on continue, which was 
down to some tidying up of the sequencer status in the stop_sequence 
routine that was added to prevent problems if you selected a new 
part chain then stopped the sequencer before it became active.
I've posted a build with this fixed, but since I'm not really set up 
to check this thoroughly myself at the moment, it's definitely a 
beta.

Cheers,
Colin f