Brief:Switching to domElement coordinates
BUGZID:
Summary:
This switches the "screen" variable to use the domElement's dimensions & location rather
than the window.

It also removes the "radius" variable in favor of using each dimension's value (ie
width & height)
Brief:Adding the option of disabling the "roll" outside of the trackball
Summary:
TrackballControls support for this.domElement being document and some clean up.