position the scaled object instead of the point

If we put the position on the sphere, then the ScaledObject always scales that distance, so the point stays in the same position on the screen.  If we instead position the ScaledObject, the size of the sphere stays constant, but as you zoom in, the position is updated correctly.
Get transformation matrices working correctly

Before, if a transformation matrix was set, it was overridden the next time the object was updated.  Now it disable's three.js' automatic updates if the matrix is explicitly set.
Transform cones and cylinders to match Sage's expectations
Delete support for converting sage viewpoints.

Surprisingly, Sage's viewpoint support is very poor and unused.  Apparently Sage *always* has a viewpoint of (0,0,6), and is documented as being just a stub for x3d.