OpenScad Surface Solids

The 1.0 version of the Bezier library included a simple linear extrusion of the bezier surface. The things this derives from added a quick and easy 'shell extrusion', which took into account the normals on the quads to create true 'inner' and 'outer' quads.

This thing makes a few improvements to both the normal calculations, and rearranges the libraries slightly to accomodate for future curved surface/solid things.

As a bonus, the hermite.scad file is thrown in. At the moment, it only ha