Analogue-sequencer

Folks,

This update has a significant but not immediately obvious change to 
the tempo generation. The timer values for any given tempo are now 
calculated on the fly (rather than using a lookup table), so I've 
been able to increase the tempo range to 30BPM to 253BPM in 0.1BPM 
steps.
The tempo knob works as before. The data knob now acts as a 
tempo 'fine tune' (TR808 style;) when used while holding the FUNC 
key.
One side effect of the change to tempo generation is that bank 
initial tempos you have set will need to be reset - the values are 
stored differently, and there was no easy way to know if they should 
be converted.

This build also changes the 'bank' select softkey behaviour.
Previously, changes to the current part were lost when you changed 
bank. I fixed this, but then needed a way to defeat the part save, 
as you can with FUNC+part when switching between parts.
So you now need to hold 'bank' (F1) and then press the step key for 
the new bank - there's no longer a sub-menu. The current part will 
be saved as the new bank is selected, unless you hold FUNC+F1+step 
number, when the part will not be saved.
It seems a bit more logical to me this way, but comments are welcome.

More to come soon. I'm hoping to 'finish' P3 very shortly so I can 
get on with other things...

Cheers,
Colin f