Add widthN to signature

--- a/src/Pure/General/markup.ML	Tue Jul 10 13:12:53 2007 +0200
+++ b/src/Pure/General/markup.ML	Tue Jul 10 15:45:34 2007 +0200
@@ -17,6 +17,7 @@
   val fileN: string
   val positionN: string val position: T
   val indentN: string
+  val widthN: string
   val blockN: string val block: int -> T
   val breakN: string val break: int -> T
   val fbreakN: string val fbreak: T