title: Application access its own version in mercurial repository
body: <p>I have application I want to print out (in "about" box) its revision/version from mercurial. Suppose it is revision <code>deadbeef</code> so it will know that. In old times in CVS could use something like <code>$Revision$</code> to substitute automatically.</p>
  
  <p>What is best practice with Mercurial for this?</p>