One-point sort-of works

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

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

src/main/scala/leon/synthesis/Rules.scala

src/main/scala/leon/synthesis/Solution.scala

src/main/scala/leon/synthesis/Synthesizer.scala

src/main/scala/leon/synthesis/Task.scala