Reworks the implementation for how knots are interpreted when importing
NURBS in .obj format. It refactors each test into a separate function
and simplifies functions using a 'multiplicity sequence' which counts
repeated occurances of knot values (or their 'multiplicity'). Making
comparisons simpler, clearer, and with improved correctness.
With regard to regression tests behavior is almost the same, noticable
difference is consideration of cyclic. Allowing curves with multiplicity
at the endpoints to be cyclic (so Bezier curves can be cyclic given
one repeated point). Untested behavior may also have been 'refined'
(changed), but additional tests would be needed to identify those cases.
Pull Request: https://projects.blender.org/blender/blender/pulls/138778
bc0913240f