enable show_markup by default (approx. double output size);

--- a/src/Pure/System/isabelle_process.ML	Sat Sep 29 18:23:46 2012 +0200
+++ b/src/Pure/System/isabelle_process.ML	Sat Sep 29 19:28:03 2012 +0200
@@ -193,6 +193,8 @@
     val _ = OS.Process.sleep (seconds 0.5);  (*yield to raw ML toplevel*)
     val _ = Output.physical_stderr Symbol.STX;
 
+    (* FIXME proper system options *)
+    val _ = Printer.show_markup_default := true;
     val _ = quick_and_dirty := false;
     val _ = Goal.parallel_proofs := 4;
     val _ =