and requests to a separate list. It's messy, because I have to make
a deep copy (e.g. of the remap list for the groups, or Expr *
stuff) of some things. Others (e.g. the polygon or mesh) will be
regenerated, so they should be discarded, but they must not get
double-freed.
In any case, works superficially. And fix a few memory leaks
unrelated to this, and remove some dead code.
[git-p4: depot-paths = "//depot/solvespace/": change = 1775]