removed parse_element -- no longer fits to liberal parse!

--- a/src/Pure/General/yxml.ML	Sun Aug 17 21:11:08 2008 +0200
+++ b/src/Pure/General/yxml.ML	Sun Aug 17 21:11:24 2008 +0200
@@ -21,7 +21,6 @@
   val element: string -> XML.attributes -> string list -> string
   val string_of: XML.tree -> string
   val parse_body: string -> XML.tree list
-  val parse_element: string -> string * XML.attributes * XML.tree list
   val parse: string -> XML.tree
 end;
 
@@ -124,8 +123,6 @@
   | [] => XML.Text ""
   | _ => err "multiple results");
 
-val parse_element = parse #> (fn XML.Elem elem => elem);
-
 end;
 
 end;