Parametric spiral generator

OpenScad's rotate_extrude module has a few limitations, particularly in the version I have. Later versions have addressed the lack of an angle parameter, but I needed something similar to how linear_extrude can do twist and scale, and to generate spirals by offsetting the shape during the rotation.
A comment on a forum somewhere (sadly I don't remember where) suggested using the hull module to accomplish this, which turned out to be an effective method. I kept on adding features, because frankly, I couldn't resist...
I don't quite understand how the Customizer draw_polygon tool works, it only seems to handle simple shapes well

Update (2018-12-15):
I added a Möbius strip to the sample shapes, and fixed a 1 degree math error

Update:
As was pointed out by AKADAP, the hull module is only effective with convex shapes. As a workaround, you can now do difference, intersection, and join operations on the shapes, which will allow you to build up non-convex shape from convex primitives