title: Yii2 page title other than inherit controller from another class tha controller
body: <p>In my <a href="/questions/tagged/yii2" class="post-tag" title="show questions tagged &#39;yii2&#39;" rel="tag">yii2</a> controller's action, the page title may be set as follows:</p>
  
  <pre><code>$this-&gt;view-&gt;title .= ' | Some title';
  </code></pre>
  
  <p>The problem here, it is not seem to have a default title for the whole of the application. i.e My site name | the page title.</p>
  
  <p>The only way that I, currently, know to work is to make another controller class inherited from the <code>controller</code> class and the define or set <code>$this-&gt;view-&gt;title</code>  define it in the construction method, then inherit all of my controllers from this class like the following:</p>
  
  <pre><code>namespace common\controllers
  use Yii;
  use yii\web\Controller;
  
  class MainController extends Controller
  {
     function __construct()
     {
       $this-&gt;view-&gt;title = 'My site name ';
     }
  }
  </code></pre>
  
  <p>Then in any controller I should extend from <code>MainController</code>.</p>
  
  <p><strong>The question is:</strong> </p>
  
  <p>Is there any configuration way or bootstrap way to set a default value for the page title, then I can concatenate another value to it through the action?</p>