Maps/Sets have explicit types, remove Empty/NonemptySet/Map

src/main/scala/leon/codegen/CodeGeneration.scala

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/Constructors.scala

src/main/scala/leon/purescala/ExprOps.scala

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

src/main/scala/leon/solvers/smtlib/SMTLIBCVC4Solver.scala

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

src/main/scala/leon/solvers/smtlib/SMTLIBZ3Solver.scala

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

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