Tube mesh extrusion library for OpenSCAD

This is a library for generating "tube-like" meshes that join a number of cross-sections. For instance, one could use this for a wing profile, or a sphere, or thread.

The cross-sections don't have to planar, nor do they have to have the same number of points, but self-intersection of the resulting tube is likely to be a problem.

There is some optimization done to make triangles in the meshes be closer to equilateral.

One of the cool things one can do with this is "morph" between two pla