Add wrapper support for custom menus

[Jimmi08]

Motivation

Minimalize number of needed template keys for custom menus

Proposed Solution

Adding support for wrappers in renderMenu() method:
$page_shortcodes->setVars($page)->wrapper('menu/'.$page['menu_template'] );
to menu handler.

Thanks

[Jimmi08]

This is example of use:
Without wrapper I would need two templates with button and without button.