title: Why PHPExcel_IOFactory can read ? almost ? all files via the HTML Reader
body: <p>I have an input type file in my <code>form</code>, and I've give all type of most used extension to test if I can reach the <a href="https://github.com/PHPOffice/PHPExcel/blob/1.8/Classes/PHPExcel/IOFactory.php#L287" rel="nofollow">Exception</a> :</p>
  
  <pre><code>throw new PHPExcel_Reader_Exception('Unable to identify a reader for this file');
  </code></pre>
  
  <p>All my tests are not conclusive enought since all of common used extension use the HTML Reader, the others <a href="https://github.com/PHPOffice/PHPExcel/blob/1.8/Classes/PHPExcel/IOFactory.php#L222" rel="nofollow">here</a> use the correct expected reader with my code :</p>
  
  <pre><code>public function initExtract(SomeDeps $deps, array $document)
      {
          libxml_use_internal_errors(true);
          $fileType = \PHPExcel_IOFactory::identify($document['tmp_name']);
          $reader = \PHPExcel_IOFactory::createReader($fileType);
          $this-&gt;excel = $reader-&gt;load($document['tmp_name']);
  
          var_dump($reader, $this-&gt;excel);
      }
  </code></pre>
  
  <p>I was wondering then why <code>PNG, JPG, GIF, PDF or TXT</code> used the <a href="https://github.com/PHPOffice/PHPExcel/blob/1.8/Classes/PHPExcel/Reader/HTML.php" rel="nofollow">HTML Reader</a> and are readable ?
  And why there is no test for this reader with <a href="https://github.com/PHPOffice/PHPExcel/blob/1.8/Classes/PHPExcel/Reader/HTML.php" rel="nofollow">this method</a> to determine if exist a HTML DOM in the provided document ?
  Just a "&lt;" is not enought IMO</p>
  
  <p>Did I missed something ? Is the Exception above really used ? For what extension ?</p>
  
  <p>This is for determine precisely what extension I have to check in <code>formValidation</code> because PhPExcel is maybe too much permissive.</p>