Quantifier improvements + invariant preservation in program transforms

src/main/scala/leon/evaluators/RecursiveEvaluator.scala

src/main/scala/leon/frontends/scalac/CodeExtraction.scala

src/main/scala/leon/purescala/DefOps.scala

src/main/scala/leon/purescala/Definitions.scala

src/main/scala/leon/purescala/Expressions.scala

src/main/scala/leon/purescala/PrettyPrinter.scala

src/main/scala/leon/purescala/Quantification.scala

src/main/scala/leon/solvers/ADTManager.scala

...main/scala/leon/solvers/combinators/UnrollingSolver.scala

src/main/scala/leon/solvers/smtlib/SMTLIBCVC4Target.scala

src/main/scala/leon/solvers/smtlib/SMTLIBSolver.scala

src/main/scala/leon/solvers/smtlib/SMTLIBTarget.scala

src/main/scala/leon/solvers/smtlib/SMTLIBZ3Target.scala

src/main/scala/leon/solvers/templates/LambdaManager.scala

.../scala/leon/solvers/templates/QuantificationManager.scala

...main/scala/leon/solvers/templates/TemplateGenerator.scala

src/main/scala/leon/solvers/templates/TemplateManager.scala

src/main/scala/leon/solvers/templates/UnrollingBank.scala

src/main/scala/leon/solvers/z3/AbstractZ3Solver.scala

src/main/scala/leon/solvers/z3/FairZ3Solver.scala