Add match-like "passes" notation to denote IO-tests

library/lang/package.scala

src/main/scala/leon/frontends/scalac/ASTExtractors.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/Trees.scala

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