Merge renderChildren() and renderHTMLChildren()

Summary: `renderChildren()` now returns array which isn't ideal but I prefer it to having two methods.

Test Plan: None.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4910

src/view/page/menu/PhabricatorMainMenuGroupView.php

@@ -33,7 +33,7 @@ final class PhabricatorMainMenuGroupView extends AphrontView {
       array(
         'class' => implode(' ', $classes),
       ),
-      $this->renderHTMLChildren());
+      $this->renderChildren());
   }
 
 }