New OMR WebGL Render Engine

[Lasse Deleuran]

This breaks panning (Command drag on a Mac, probably Control Drag on Windows). As far as I can tell, panning is now in global coordinates, instead of view coordinates.

I have compared the latest and previous revision. Both have panning work on the floor plane.

This is opposed to how panning works in Orthographic mode (See sample_view.htm). If you know how to switch between the panning modes without changing the camera type, then I can implement the switch in the UI.