remove usage of FunctionType and AnonymousFunction

src/main/scala/leon/Evaluator.scala

src/main/scala/leon/FunctionTemplate.scala

src/main/scala/leon/plugin/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/TypeTrees.scala

src/main/scala/leon/solvers/RandomSolver.scala

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