Also fixes some plot bugs with arcs.
Also moves polygonization of arcs (when required) in plotting code
from 5 degrees to calculated based on ARC_HIGH_DEF.
Fixes https://gitlab.com/kicad/code/kicad/issues/5017
Calling UpdateItem() may be performed by in a common loop, e.g. for(
SCH_ITEM* item : GetScreen()->Items() ) or similar. We cannot call
GetScreen()->Update( SCH_ITEM* ) in this routine as it will remove and
re-add the item to the RTree, invalidating iterators. If needed, the
items need to be cached to an external container before updating
Fixes https://gitlab.com/kicad/code/kicad/issues/9318
They don't define a KiCad string class, so the header file name was
somewhat misleading. But the fact that they didn't match definitely
made coding more difficult.