Alternative RingGeometry Fix

This change removes the extra triangles connecting the ends of a partial RingGeometry, and sets the minimum number of concentric bands to one, like merpnderp's #4878 does. However, it also:

- Eliminates the redundant vertices created when the ring is complete, and welds the seem
- Prevents values of thetaLength greater than 2 * PI which would create overlapping geo
- Removes some redundant calculation form the process of Ring Geometry face generation