Improvements to scene parsing API

[yamins81]

1. have little indicators showing what the rotation axes are for each rotation wheel
2. have sliders for size and position

[yamins81]

I think users will expect all the rotation knobs to be such that the clockwise (or counterclockwise) direction produces the shown rotation in the little image. Currently, the first two knobs, the counterclockwise direction produces the shown rotation, whereas the third knob acts clockwise to get the shown rotation. I think would prefer all to be clockwise go get the shown rotation ...but consistency is most important.