Improve transition from 3D to 2D

[Nesciosquid]

Transitioning back to the 2D view from the 3D view is a bit of a hack, since it's possible to have moved the 3D camera in such a way that your view of the device is very skewed. Because of this, the 2D view 'snaps' back to the part of the design that's nearest where the 3D camera was, so as to keep it within view.

This behavior could be improved, but figuring out the right way to represent this transition is tricky.

See: The switchTo2D() function in pageSetup.js.