Missing features:
-----------------
* Add a feature to saturate user-given constraints
* remove spurious edges from the shortest error trace and order
  the nodes.
* Enable printing out statistics for focus/coerce.
* draw the structures inside the nodes of the transition relation
* -join ind seems to be crashing.

Bugs:
-----
* -tr:dot/-tr:tvs don't work with -join part/ind
* documentation: defining formulae / update formula
  "the formula's free variables should match the variable given in the parentheses
   (with the exception of precondition free variables explained later)."

Done:
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* Add isomorphism checks for -join conc
* -join rel seems to be awfully slow - fixed with better hashing
* reporting abs unary predicates seems to be wrong (0) - fixed
* shortest abstracrt error trace
  Check the bug in pruneForAbstractErrorTrace()
* Figure out how to treat constraint breaches that do not stop the analysis.
  Should the users be warned about soundsness issues in such a case?
  Fix: the printouts indicate that these constraints lead to possible performance
  issues.
* Differencing doesn't handle name clashing between the variables that are
  the arguments of the predicates being updated and the bound variables from
  precondition formulae.
  Fixed by checking for name clashes in actions.
* dump constraints information to log.
  Solution: I added the tvla.coerce.debug option to tvla.properties
  I refactored the code for printing constraints dependencies into a different
  method in AdvancedCoerceOld and calling it from AdvancedCoerce.init thereby
  solving a null pointer exception bug, which results from executing this
  code prior to building the connected components graph for the constraints.
