Suspect div by zero case.

[projectPythonator]

technically this case should only really happen in circumradius and circumcircle functions when you have 3 horizontal or vertical collinear points. if a d == 0 check is moved before you divide by d (or det) you can avoid it, alternatively you can also check for collinear points directly if wanting to detect them.

[abellgithub]

I can certainly prevent the divide-by-zero, but the question is what should be done at that point. I'm not sure how much trouble this is worth unless there's a good test case.