Break the inner-compiler in different ways so that it works with sbt test.

src/main/scala/leon/Settings.scala

@@ -22,5 +22,8 @@ case class Settings(
   val synthesis: Boolean      = false,
   val xlang: Boolean          = false,
   val verify: Boolean         = true,
+  // This is a list of directories that is passed as class-path of the inner-compiler.
+  // It needs to contain at least a directory containing scala-library.jar, and
+  // one for the leon runtime library.
   val classPath: List[String] = Settings.defaultClassPath()
 )

src/main/scala/leon/plugin/ExtractionPhase.scala

@@ -13,7 +13,8 @@ object ExtractionPhase extends LeonPhase[List[String], Program] {
 
     val settings = new NSCSettings
 
-    settings.extdirs.value = ctx.settings.classPath.mkString(":")
+    //settings.extdirs.value = ctx.settings.classPath.mkString(":")
+    settings.usejavacp.value = true
 
     val compilerOpts = args.filterNot(_.startsWith("--"))