Fixes#602. Collinear-edge merging, piece naming and the dialog preview each work in one pass instead of quadratic loops; the issue's example goes from 86 s to 5.1 s.
Box, Cylinder, Sphere, Torus and Coil go where a face or vertex was picked before starting them: centred on the point, standing on a planar face (a box on an axis-aligned face sits on it; cylinders and coils take the face normal as axis). The dialog shows the position with a button to place at the origin instead. Fixes#580.
Co-authored-by: lasselian <lassesorensen80@gmail.com>
Lasse Lian