Multiple menu items per node with category_menu

Category_menu currently only ever creates one menu item per node, whether that node is a containeri, a categoryi, or an assigned nodei. If the node is a container or a category and it has multiple parentis, then the parent with the lightest weighti is used as the menu item parent. If the node is an assigned node, then the category assigned to it with the lightest weight is used as the menu item parent.

But this is not ideal - category_menu can do better. It is possible to enhance category_menu to support creating a menu item for every parent (or assigned category) of every node that it manages. The core menu system in Drupal 4.7 has support (albeit poorly documented) for 'menu shortcuts' - that is, multiple menu items for a single Drupal path. I believe that the way it works is that the first menu item created is treated as the 'primary' menu item, and this item is the one used for breadcrumbs (much like the first alias created for a path is treated as the 'primary' alias, which is used for outputting links).

This feature would not have any impact on breadcrumbs or on navigation links, as there is no way to represent multiple parents in these elements. It would also have no impact on table of contents, as this element already supports multiple parents (since it's generated purely by category_display, and is not dependent on category_menu). However, it would have an impact on menu links, that are displayed either in a side block, or in the primary/secondary links area.

Since this feature would add significant overhead to the maintenance of category-related menu items, I'm thinking of making it a feature that can be disabled.