Little BIG improvements

A list of small changes that can have a huge impact on workflow.

a) Option to invert direction of shift+scroll wheel.

b) Extend markers to have the line cover the whole track view (like every other DAW) *along with it and the chord track,etc being visible in editors.

c) Ability to change voicing in the chord track itself.

d) Ability to see grid lines in variaudio.

e) Ability to snap cursor to closest grid line when locating by clicking on empty space.