Splines on the scene

I'm improving my sources concerning curves. Considering their math properties, splines are the classical choice.

I have been trying to do a very robust and modularized implementation. I'm preparing an infrastructure that will be used in future for interactive drawing of curves by the final user.

Interactive drawing is a very interesting challenge that asks special planning, cause it can require immediate answers for nontrivial operations.

The picture shows a multi-curve created by "self point parametrization". A curve can be created by "control point parametrization" as well.