SetPosition() only changes the base position of tracks, we need to use
Move() to move the whole element.
This also cleans up white space and group handling in ratsnest
Fixes https://gitlab.com/kicad/code/kicad/issues/5188
This introduces layer handling to a lot of the geometry routines.
Many of them don't do much with it now, but it does help multi-layer
zones and will help when padstacks are implemented.
jean-pierre charras
Seth Hillbrand
Jeff Young
Qbort