title: Display error message from Admin_Controller
body: <p>I had create core/Admin_Controller.php and I created page controller but when I run page controller there is error displaying
  "Fatal error: Class 'Admin_Controller' not found in D:\xampp\htdocs\myproject\application\controllers\admin\Page.php on line 4"</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>class Admin_Controller extends MY_Controller
  {
      function __construct()
      { 
          
          parent::__construct();
  
        
      }
  
  }</code></pre>
  </div>
  </div>
  
  page controller</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>defined('BASEPATH') OR exit('No direct script access allowed');
  
  class Page extends Admin_Controller {
  
   public function __construct()
   {
    parent::__construct();
    $this-&gt;load-&gt;model('admin_m');
    $this-&gt;load-&gt;model('page_m');
   }
  
   public function index(){
    $data['title'] = 'Press Release';
          $data['page'] = $this-&gt;page_m-&gt;show_list();
          $this-&gt;load-&gt;view(THEME_DIR_ADMIN.'common/admin_header');
          $this-&gt;load-&gt;view(THEME_DIR_ADMIN.'page/list', $data);
          $this-&gt;load-&gt;view(THEME_DIR_ADMIN.'common/admin_footer');
   }
  } </code></pre>
  </div>
  </div>
  
  Do I need to update any file?</p>