Users Set the Parent Menu Item to "Add a main menu item"

Patch contains a theme.inc check for an empty 'main_menu' and add the appropriate link taken from the removed menu_add in default.profile. Switching theme still shows the link for the main menu.

afaik we need count because in line 1941

  $variables['main_menu']         = theme_get_setting('toggle_main_menu') ? menu_main_menu() : array();

is set to an empty array and

// includes/menu.inc
function menu_main_menu() {

returns an array.

But I haven't tested the toggle_main_menu yet :(

- moved theme.inc code a few lines up
- included test for toggle_main_menu
- wrapped t() arround 'Add a main menu link'

Not sure why this test failed.

Rebuild patch

* The menu-item "Add a main menu item" for main-menu is just a link added through theme.inc
* When adding a menu-item to the main-menu this link disappears.
* When removing _all_ menu-items from main-menu this link appears.
* This is only available when main-menu is configured to show up.

Bojhan adviced to postpone this feature. This feature is now confusing with regard to the toolbar.

According to #582734: Removal of Add a main menu link this could be closed. #473268: D7UX: Put edit links on everything adds links for everything :)