FiniteSets should hold Sets, otherwise {1,2} != {2,1}

src/main/scala/leon/codegen/CompilationUnit.scala

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

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

src/main/scala/leon/purescala/Extractors.scala

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

src/main/scala/leon/purescala/ScalaPrinter.scala

src/main/scala/leon/purescala/TreeOps.scala

src/main/scala/leon/purescala/Trees.scala

src/main/scala/leon/purescala/TypeTreeOps.scala

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

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

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

src/main/scala/leon/synthesis/rules/Tegis.scala

src/test/scala/leon/test/evaluators/EvaluatorsTests.scala