Function createMenuIfNotExists

Creates a menu set from the items passed. But only if the menu set does not already exist

Package: plugins
Author: Stephen Billard (sbillard), Malte Müller (acrylian)
Located at zp-extensions/menu_manager.php

Parameters summary
`array`	`$menuitems`	<p>items for the menuset array elements: 'type'=>menuset type 'title'=>title for the menu item 'link'=>URL or other data for the item link 'show'=>set to 1:"visible" or 0:"hidden", 'nesting'=>nesting level of this item in the menu heirarchy</p>
`string`	`$menuset = 'default'`	current menuset