today: build two more valence for beta testers.

a total of 4 are now in existence.

Also implemented button locking in loop modes.  Holding down a function button for 4 seconds will lock CV1 to that function.  After letting go of the button it acts as if it is still held, meaning that CV1 can now be changed without physically holding the button down.  This allows external CV control of pattern select, gate duty, and slide interpolation types.  Pressing any button exits this mode.  Also works in Record modes.