title: Make relative links into absolute ones
body: <p>I am requesting the source code of a website like this:</p>
  
  <pre><code>&lt;? $txt = file_get_contents('http://stats.pingdom.com/qmwwuwoz2b71/522741');
  echo $txt; ?&gt;
  </code></pre>
  
  <p>Bu I would like to replace the relative links with absolute ones! Basically,</p>
  
  <pre><code>&lt;img src="/images/legend_15s.png"/&gt; and &lt;img src='/images/legend_15s.png'/&gt;
  </code></pre>
  
  <p>should be replaced by</p>
  
  <pre><code>&lt;img src="http://domain.com/images/legend_15s.png"/&gt; 
  </code></pre>
  
  <p>and</p>
  
  <pre><code>&lt;img src='http://domain.com/images/legend_15s.png'/&gt;
  </code></pre>
  
  <p>respectively. How can I do this?</p>