Thicken now moves faces through the same mover as Offset Surface. Spheres, cones, tori and B-spline faces thicken as well as planes and cylinders, and a thickness that would fold a curved face over is refused. Where thickened faces meet at a sharp edge, a wall closes the gap and corners are closed with flat patches. Thickening into an inside corner is still refused with a clear message.
Closes#765.
Co-authored-by: jyviko <[email protected]>
