Arpeggio note repeats

( proposed new arpeggiator function )
Here's the latest from the lab (sofa, non-ergonomic posture).
![arpeggio-repeats](https://cloud.githubusercontent.com/assets/6368949/2900928/2a414e6c-d5ce-11e3-851d-53c626dbb6de.png)

It simply lets you set the number of times a note should be repeated before the arpeggiator advances.
I'm not 100% sure when to cast the potentiometer values(floats) as an int.
There's more functions I'd like to try out in the arpeggiator so maybe not commit it without a discussion or we'll run out of GUI real estate.