Wrap image on curved surface for OpenSCAD

Python script to read a grey-scale PNG image and generate an OpenSCAD source file. The image is embossed onto/etched into the curved surface, which represents a solid object. The surface may be any fragment of a conic (including cylindrical) surface, or any other mathematically defined surface.

Based on source code by Philipp Tiefenbacher (wizard23) -- since OpenSCAD now allows polyhedron faces with more than 3 points, this is much simpler than Philipp's version, and it was possible to gener