removed pointless / outdated keywords, superseded by specific Token_Markup.Marker;

--- a/src/Tools/jEdit/src/modes/isabelle.xml	Sun Jul 07 17:30:16 2013 +0200
+++ b/src/Tools/jEdit/src/modes/isabelle.xml	Sun Jul 07 17:52:13 2013 +0200
@@ -29,14 +29,5 @@
       <BEGIN>"</BEGIN>
       <END>"</END>
     </SPAN>
-    <KEYWORDS>
-      <KEYWORD2>header</KEYWORD2>
-      <KEYWORD1>theory</KEYWORD1>
-      <KEYWORD2>imports</KEYWORD2>
-      <KEYWORD2>keywords</KEYWORD2>
-      <KEYWORD2>uses</KEYWORD2>
-      <KEYWORD2>begin</KEYWORD2>
-      <KEYWORD2>end</KEYWORD2>
-    </KEYWORDS>
   </RULES>
 </MODE>