More GUI additions

Added toggles for faces and edges.
Stroke changes to white when showing edges, but no faces.
Added Catmull-Clark subdivision toggle. (smootihing) - currently very
slow.
Removed x and y value sliders - they had no noticable effect on the
model.

Added Sphere inversion. Doesn't seem to work. Needs troubleshooting.

Started implementing center draggable area for view rotation. Will have
to refine before implementing