Shape intersection

Finalized the first version of shape intersection algorithm so that when closed 2D shapes are drawn they are intersected with the other shapes drawn. This also works well with the AutoGroup algorithm that automatically creates closed wires from opened wires drawn (like arc, line, spline).
On the screenshots below you can see various shapes intersecting (including a rectangle generated with AutoGroup). Some of the small shapes resulted after intersection are extruded. There are still problems to be solved: it interferes with Cut that generates a single shape after applying, the small parts on which a feature like extrude is applied should be eliminated from the intersection algorithm list.