title: Why don't I have access to setReadDataOnly() or enableMemoryOptimization() in PHPExcel?
body: <p>I've downloaded <a href="http://phpexcel.codeplex.com/" rel="nofollow noreferrer">PHPExcel 1.7.5 Production</a>.</p>
  
  <p>I would like to use <strong>setReadDataOnly()</strong> and <strong>enableMemoryOptimization()</strong> as <a href="http://phpexcel.codeplex.com/workitem/14701" rel="nofollow noreferrer">discussed in their forum here</a> and in <a href="https://stackoverflow.com/questions/1859599/phpexcel-formatting-gets-lost-when-editing-from-code">stackoverflow questions</a>.</p>
  
  <p>However when I use them, I get a <code>Call to undefined method</code> error.</p>
  
  <p><strong>Is there another version or some plugin or library that I have not installed? 
  What do I have to do to access these methods?</strong></p>
  
  <pre><code>$objPHPExcel = PHPExcel_IOFactory::load("data/".$file_name);
  $objPHPExcel-&gt;setReadDataOnly(true); //Call to undefined method
  $objPHPExcel-&gt;enableMemoryOptimization(); //Call to undefined method
  </code></pre>