The clearance between two zones could be rather slow. This was in part
to trying to do triangle-triangle collisions between zones when we only
need outline collision and in part to the shape_line_chain collision
routine. The shape_line_chain collisions don't need to recreate
segments on each iteration and should instead create them once and using
this to check all collisions
Fixes https://gitlab.com/kicad/code/kicad/-/issues/17327
Previously the snap points computed for oval pads didn't get all the
points correct. This breaks out the "find snap points for ovals"
into a function, reworks the logic, adds some tests.
Also adds "extremum points" when the oval isn't exactly H/V.
Fixes: https://gitlab.com/kicad/code/kicad/-/issues/15594
Using the new ITEM_MODIFICATION_ROUTINE system, drop in two new
tools: chamfer and line extend. These are two geometric operations
that are relatively common when editing footprints in particular.
Chamfer delegates the geometric calculations to a dedicated unit
in kimath/geometry.
Seth Hillbrand
Roberto Fernandez Bautista
Alex Shvartzkop
Jeff Young
John Beard
Jon Evans
Marek Roszko