more standard main method;

--- a/src/Pure/System/main.scala	Tue Jul 17 13:07:28 2012 +0200
+++ b/src/Pure/System/main.scala	Tue Jul 17 14:33:23 2012 +0200
@@ -11,7 +11,7 @@
 
 object Main
 {
-  def main(args: Array[String]) =
+  def main(args: Array[String])
   {
     val (out, rc) =
       try {