Simple Screw Thread Library Turbo

The original library is from marcaxi with improvements by rubisco2000. I rewrote it to create a single polyhedron instead of using the hull operator and unions to join different triangles together, this brings huge performance improvements. On my machine the example parts originally took about 1min 24sec to render, with the improvements 12sec.
The created geometry is almost exactly the same, only a really small tolerance is used so points don't overlap. The only problem is that the preview does not work correctly, but the rendered objects are okay.