Minor fixes

Fixed some minor annoyances:
– Select Master weirdness
– Chan Mode doesn't terminate anymore if you select a track twice
– Mixer scroll takes now takes tracks into account
– Bank switch ends on last track (not forced to steps of eight anymore)
– Some Undo weirdness
– Last param of Scribble Strip didn't update sometimes
– Scribble Strip shows track names in Chan Mode if you touch a fader (or
encoder when flipped)