refactoring

src/main/scala/Example.scala

src/main/scala/lisa/kernel/proof/Judgement.scala

src/main/scala/lisa/settheory/SetTheoryDefinitions.scala

src/main/scala/lisa/settheory/SetTheoryTGAxioms.scala

src/main/scala/lisa/settheory/SetTheoryZAxioms.scala

src/main/scala/lisa/settheory/SetTheoryZFAxioms.scala

src/main/scala/proven/DSetTheory/Part1.scala

src/main/scala/proven/ElementsOfSetTheory.scala

src/main/scala/proven/tactics/Destructors.scala

src/main/scala/proven/tactics/ProofTactics.scala

...main/scala/proven/tactics/SimplePropositionalSolver.scala

src/main/scala/utilities/KernelHelpers.scala

src/main/scala/utilities/tptp/KernelParser.scala

src/main/scala/utilities/tptp/ProblemGatherer.scala

src/main/scala/utilities/tptp/package.scala

src/test/scala/lisa/kernel/EquivalenceCheckerTests.scala

src/test/scala/lisa/kernel/FolTests.scala

src/test/scala/lisa/kernel/IncorrectProofsTests.scala

src/test/scala/lisa/kernel/ProofTests.scala

src/test/scala/lisa/proven/ElementsOfSetTheoryTests.scala