Feature request: Start and end frames in Pixels.

[dj spiff]

It would be very handy to be able to generate only a portion of the total scene output. It could also be a simple loop offset. A way to nudge the scene into a better position on a MIDI knob. Transport control would be a nice touch to aid in knob mapping as well. Or just be able to MIDI map a test knob directly to pixels' frame position.

Thanks!