Interpolated lofting between two 3D vertex lists.

Adapted from https://www.instructables.com/Loft-in-OpenSCAD/ by better call it art, but there's no proper way to mark this submission as a remix on Thingiverse, because the source is off-site, and of course that wouldn't work.

I hackjob-fixed it for backwards-compatibility to 2015.03 and added some extra stuff. It now supports convexity specification and can accept vertex lists with improper winding order.

The SCAD file includes a set of demos, one of which is included here as an STL for visualization.