exported break reference

--- a/src/Pure/Thy/thy_output.ML	Thu Jan 15 12:16:51 2009 +0100
+++ b/src/Pure/Thy/thy_output.ML	Thu Jan 15 12:55:38 2009 +0000
@@ -11,6 +11,7 @@
   val quotes: bool ref
   val indent: int ref
   val source: bool ref
+  val break: bool ref
   val add_commands: (string * (Args.src -> Toplevel.node option -> string)) list -> unit
   val add_options: (string * (string -> (unit -> string) -> unit -> string)) list -> unit
   val defined_command: string -> bool