add a method to write a program to a file in valid scala syntax

src/main/scala/leon/TestGeneration.scala

@@ -43,7 +43,7 @@ class TestGeneration(reporter: Reporter) extends Analyser(reporter) {
 
     val Program(id, ObjectDef(objId, defs, invariants)) = program
     val testProgram = Program(id, ObjectDef(objId, testFun +: defs , invariants))
-    println("New program:\n" + ScalaPrinter(testProgram))
+    testProgram.writeScalaFile("TestGen.scala")
 
     reporter.info("Running from waypoint with the following testcases:\n")
     reporter.info(testcases.mkString("\n"))

src/main/scala/leon/purescala/Definitions.scala

@@ -54,6 +54,15 @@ object Definitions {
     def caseClassDef(name: String) = mainObject.caseClassDef(name)
     def allIdentifiers : Set[Identifier] = mainObject.allIdentifiers + id
     def isPure: Boolean = definedFunctions.forall(fd => fd.body.forall(Trees.isPure) && fd.precondition.forall(Trees.isPure) && fd.postcondition.forall(Trees.isPure))
+
+    def writeScalaFile(filename: String) {
+      import java.io.FileWriter
+      import java.io.BufferedWriter
+      val fstream = new FileWriter(filename)
+      val out = new BufferedWriter(fstream)
+      out.write(ScalaPrinter(this))
+      out.close
+    }
   }
 
   /** Objects work as containers for class definitions, functions (def's) and