This patch enables all 8 combinations of Nurbs modes: Cyclic,
Bezier and Endpoint. Also removes restriction on Bezier Nurbs order.
The most significant changes are mode combinations bringing new
meaning. In D13891 is a scheme showing NURBS with same control
points in a modes, and also further description of each possible case.
Differential Revision: https://developer.blender.org/D13891
0602852860