Cleanup and initial direction tooltips.

Mesh construction was simplified. The shape is now a group of meshes,
one for each face. Corner offset to coordinate calculations are now
done via vector operations rather than manual calculation. Code was
put in place to ray cast the mouse cursor's position to determine the
face it is on; material color is changed on mouse-over. A second
orthographic scene and camera were added to display text sprites for
tooltips. Face names (directions) are shown as text sprites on
mouse-over.
Cleanup and initial direction tooltips.

Mesh construction was simplified. The shape is now a group of meshes,
one for each face. Corner offset to coordinate calculations are now
done via vector operations rather than manual calculation. Code was
put in place to ray cast the mouse cursor's position to determine the
face it is on; material color is changed on mouse-over. A second
orthographic scene and camera were added to display text sprites for
tooltips. Face names (directions) are shown as text sprites on
mouse-over.
Merge branch 'tooltips' of github.com:pinealservo/VoxView into tooltips

Conflicts:
	voxview.js
Fixing Zeuljii's URL update code that was broken during merge
Merge branch 'tooltips'