Avoid rerunning clingo on reodering of components

[stephanzwicknagl]

Avoiding the renewed call to clingo using a new justifier program might be a performance improvement, but is currently not a bottleneck. It's not certain whether clingo is actually slower than the proposed set operations.

• when the moved component is not moved past a rule with the same predicate in head: no need to recalculate anything
• other cases: use old "h" symbols (not h_new), reassign indices according to new sort, then manually do the finding of h_new.