v2.2.0

Added

• Improved FormulaFactory by avoiding creating unnecessary negations (cache pollution) during the check for complementary operands.
• Improved the NNF computation by avoiding creating unnecessary negations (cache pollution) during the recursive calls.
• Extracted the NNF computation in its own transformation class NNFTransformation.
• Moved all formula caches from the Formula class to the FormulaFactory to save memory by avoiding creating empty cache maps.
• New TermPredicate class to check whether a formula is a minterm (clause) or maxterm (DNF term).
• Extended helper classes CollectionHelper and FormulaHelper by additional convenient methods.

Fixed

• Fixed a bug in the addSoftFormula method of the MaxSATSolver class. A soft formula is now weighted properly if the soft formula is not a clause.
• Fixed a bug in the addWithRelaxation method of the SATSolver class. The CNF of the formula is now computed properly regarding the configuration of the
  solver.

Deprecated

• Deprecation of method addWithoutUnknown in class SATSolver - this method will be removed in future versions.
• Deprecation of method addWithRelaxation for propositions in class SATSolver - this method will be removed in future versions.