title: find matching 'begin' - 'end' and highlight them
body: <p>I am a newbie in developing a DSL in Xtext. I would like to add a feature of highlighting the matching start and end of a code block. In my language every function must start with 'begin' and end with 'end' and same with if conditions and loops. I need to highlight the matching/corresponding 'end' when the cursor is on the 'begin'. for example below, I need to highlight the corresponding first 'end' when the cursor is on the second 'begin':</p>
  
  <pre><code>function X 
    begin
       if a&gt;b
         begin
           a=b;
         end
     end
  </code></pre>
  
  <p>Any help with that please?</p>
  
  <p>Thanks</p>