Rotational Constructor - 2

Today I didn't get much further on the rotational constructor as such as I had to change some support structures to make it possible to continue. The rotational constructor is the first modifier of the polyhedrons which uses its own selection object. All the others use one selection and it was sufficient. But the rotational constructor has a very special need, it is not interested in the regular selection of vertices, edges or faces. Instead it has to handle selection of the points and lines of the profile curve.

To make that possible I had to break up some very old code. And that always takes a bit of time to think through and implement. Most of it should be working now, I think I am only missing one bit, the rendering should not show the vertices and edges. It currently does, but it shouldn't be hard to change.