Add back rotate when space is clicked. Add look when close to the ground and the sky is clicked.
Change look to use the geodesic normal to rotate about. Keep track of looking, panning, or rotating.
Re-add rotate in 3d tests (for mousing over space).
Stay in whatever mode the camera is in until the mouse is released.
Make tilt mouse button also look when clicking the sky.
Add looking when clicking the sky to translate and tilt mouse buttons in Columbus View.
Use abs when checking against epsilon value for plane/terrain intersection.
Make the geodesic normal a constrained axis for interaction with the sky.
Fix bad doc links.
Update CHANGES.md.
Changes after review.

Improve visualizer performance by inlining functions that the optimizer does not seem to do itself.