One extrude cutting many circles from one sketch still cut the plate once per
circle, each boolean rebuilding and re-meshing a plate grown by every hole before
it (32 circles 2 s, 128 circles 60 s). The #261 fix joined clear tools with
kernel::union_apart only in pattern replay; apply_traced now does it for every
cut with 8 or more tools (patterns included), keeping each piece's face lineage.
Jonas Wrede
829912c6c5