About 1/3 of callers to Parent() don't care if they get the immediate
parent or not, about 1/3 want only the immediate parent, and about 1/3
want the hole parent's Parent().
I had earlier changed PNS::ITEM::HOLE to override Parent() and return
the hole parent's Parent(), but since the callers are pretty evenly
split I've reverted that and added BoardItem() for callers who want the
eventual BOARD_ITEM (whether a direct parent or a grandparent).
(Also removes a dead routine so I didn't have to figure out which of
the two it wanted....)
- LINEs now own their vias optionally (depending whether a LINE with its VIA belongs to a node)
- get rid of unique_ptr on the internal NODE::Add API (and also made it private)
- make sure stack pointers are not added to the node
- use rvalue reference for NODE::Add/NODE::Replace
Manually rebased by Jeff Young <jeff@rokeby.ie> 5 April 2023
Marek Roszko
Jeff Young
Tomasz Wlostowski