Load the growler.

Even in basic mode, the iTip forms are submitted via Imples, so that Ajax
notifications are used. The page is not reloaded so basic notifications don't
work.

It's of course horribly inconsistent to use the Growler notifications here, but
it's better than not notifying the user at all. And refactoring the iTip viewer
back to work with page reloads in basic mode is a waste of time.

imp/lib/Mime/Viewer/Itip.php

@@ -80,6 +80,7 @@ protected function _render()
      */
     protected function _renderInline()
     {
+        $GLOBALS['page_output']->growler = true;
         $data = $this->_mimepart->getContents();
         $mime_id = $this->_mimepart->getMimeId();