Implement rotory encoder GUI slider

[dishmint]

It could be cool to have an infinite encoder so that I can forward / rewind a sketch. However, I would have to save the frame state. In any case, a rotary could be a nice addition to TweakPane.

[dishmint]

That shouldn't be a huge burden, because each new frame is drawn anyway. The difference is that when you let go of the slider the frames continue like a video.