Created a second admin loader for callbacks that need to generate an edit cache (for ajax callbacks)

Rolled back earlier changes to admin path schema - $panel_page->name now precedes the action verb (e.g. edit, export) again.

Reinstated the %map arg on several admin callbacks; changed the storage mechanism for the loader flags;

Removed suuuuuper crufty ajax functions - they hadn't been in use for who knows how many months, and nobody noticed :)

Fairly large reorganization, although not much change in the logic. Most notable big item is that hook_menu() and hook_menu_alter() are now separate again, and the functions have been reorganized to place the two that hook_menu() calls at the top of the file (purely for conceptual clarity).

Also switched over to the use of a 'flags' field in the router quickref table, which is where we tuck as much of our behavior-governing bitmask as possible during the actual menu build process.

We're most of the way there! Our separate data storage mechanism appears to be mostly working. Now the frontend loading needs to be done, along with the hook_menu_link_alter() stuff.

Panels Page now installs successfully, although the schema is likely going to change. The essential infrastructure for the menu system is functioning correctly. The secondary router storage mechanism, page callbacks, temporary panel data storage mechanism (for render callbacks) and a few other things need to be designed - but we're on the home stretch.

Nearly there. Just need to write the storage mechanism for overridden loaders, then can start debugging.

About three-quarters of the way through the menu system port. Most of the guts are in place, although the bitmasks need considerable work and I've yet to work out a finite solution for sticking the admin tabs in wherever they might need to be.