Add helper routine to create the 'all post type' menu items

[bobbingwide]

In WordPress 4.4 the logic that enabled a custom post type archive to be added to a menu item was included in core. The problem with the UI is you can't create the menu items before there's any content. Also it's a bit labour intensive since you have to remove the "All" prefix from the menu item.

Proposed solution

deliver a helper routine to programatically create the menu items. File create-all-post-type-menu-items.php