OpenScad Surface Solids 1.2

I was sitting around the kitchen table wondering how I could model a playground slide, or those water slide tubes.

This thing adds hermite curve/surface support to the OpenScad Surface Solids library.

The basic Hermite interpolation calculation has actually been lurking for a while, but now it's put to good usage. With this, there is now a lerp (linear interpolation), berp (bezier interpolation), and herp (hermite interpolation) in the library.

A Hermite curve is defined by two endpoin