Add examples showing how subdivision algorithm works

[dhermes]

In curve-curve-intersection.rst.

Add both a "straightforward" case and another that has to do polynomial clipping to reduce the list of candidate pairs.

This should resemble curve_intersection_potpourri.pdf, a document I had previously started during my PhD.

[dhermes]

There are a few other plots / groups of plots from a gist I made during my PhD that I'd like to incorporate into the docs.

Subdivision for Curve Intersection

Subdivision for Triangle-Triangle Intersection

Solve inverse B(s, t) = p via triangle subdivision

[dhermes]

There are a few other plots / groups of plots from my PhD

Invalid Bezier Triangle

Curve-Curve Intersection

Curved Edge Pairs Classified

Description of Triangle-Triangle Intersection Algorithm