title: The file PHPExcel_Shared_String.php is missing in the includes folder
body: <p>I have tried the change function and it did NOT work.</p>
  
  <p>I am working with PHPExcel and I keep on getting this error
  "The file PHPExcel_Shared_String.php is missing in the includes folder."</p>
  
  <p>it is not showing up as a fatel error or anything like that. It is just printing out on the screen </p>
  
  <p>I am using PHPExcel Version 1.8.0.</p>
  
  <p>IOFactory.php</p>
  
  <pre><code>/** PHPExcel root directory */
  if (!defined('PHPEXCEL_ROOT')) {
      /**
       * @ignore
       */
      define('PHPEXCEL_ROOT', dirname(__FILE__) . '/');
      require(PHPEXCEL_ROOT . 'Autoloader.php');
  }
  </code></pre>
  
  <p>mypage.php</p>
  
  <pre><code>include('../../../assets/phpexcel/Classes/PHPExcel/IOFactory.php');
  </code></pre>
  
  <p>Autoloader.php</p>
  
  <pre><code>class PHPExcel_Autoloader
  {
      /**
       * Register the Autoloader with SPL
       *
       */
      public static function Register() {
          if (function_exists('__autoload')) {
              //    Register any existing autoloader function with SPL, so we don't get any clashes
              spl_autoload_register('__autoload');
          }
          //    Register ourselves with SPL
          return spl_autoload_register(array('PHPExcel_Autoloader', 'Load'));
      }       //function Register();
  </code></pre>