Check handling of auxiliary variables after inlining

[blishko]

After resolving on some predicate in multiple clauses, the same auxiliary variable from one clause may end up in multiple clauses. This is undesirable, because it causes problems in engines that make global, not just local satisfiability checks.

Moreover, former state variables may become auxiliary in the new clause and hence they should be renamed, so they do not confuse our versioning system.

Hints:

• Look at ChcDirectedHyperGraph::contractVertex and its requiresRenamingAuxiliaryVars flag.
• Possibly add another preprocessing pass that will try to eliminate auxiliary variables after other rewriting passes.