Adding support for compressing VCs during checking

...in/scala/leon/invariant/engine/InferInvariantsPhase.scala

src/main/scala/leon/invariant/engine/InferenceContext.scala

src/main/scala/leon/invariant/engine/InferenceEngine.scala

src/main/scala/leon/invariant/engine/SpecInstantiator.scala

...main/scala/leon/invariant/factories/TemplateFactory.scala

...scala/leon/invariant/factories/TemplateInstantiator.scala

src/main/scala/leon/invariant/structure/Constraint.scala

src/main/scala/leon/invariant/structure/Formula.scala

...in/scala/leon/invariant/templateSolvers/CegisSolver.scala

...la/leon/invariant/templateSolvers/FarkasLemmaSolver.scala

...ala/leon/invariant/templateSolvers/NLTemplateSolver.scala

.../invariant/templateSolvers/NLTemplateSolverWithMult.scala

...scala/leon/invariant/templateSolvers/TemplateSolver.scala

...ain/scala/leon/invariant/util/ExpressionTransformer.scala

src/main/scala/leon/invariant/util/FlatToUnflatExpr.scala

...n/scala/leon/invariant/util/LinearRelationEvaluator.scala

src/main/scala/leon/invariant/util/Minimizer.scala

src/main/scala/leon/invariant/util/SelectorToCons.scala

src/main/scala/leon/invariant/util/SolverUtil.scala

src/main/scala/leon/invariant/util/Stats.scala