change external button input to expression pedal input

it was always my plan to add expression pedal input and now I have done it - this required replacing the external switch TS jackwith a TRS jack and moving code around to match

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Update hans.ino

editing values by pressing a button many times over is not fun so I added a repeat button function
when you hold the button longer than x time (currently 250ms) the value will automatically increase/decrease every x time
also did some code cleaning as there was a lot of copy/paste/change the first time around.. expect more of this as I am further embarassed by what I've done

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