"goto" query param considered harmful

Any redirects will use the RT 4 "NextPage" session store used by login.
Put About link into the menu
Update our MakeClicky override which adds rel="nofollow"

Inserting spaces is no longer necessary in RT 4.
Replace old Tabs callback with the new one

ContactInfo was handled by the old callback, and is now positioned at
the bottom of pages for lack of a better location in RT 4.
Use a better copy of the CPAN logo
Delegation is lone gone in 4.0
Rejigger About page and create a separate Usage page

It's now easier to point to usage than "Look at the login page",
especially when a person is already logged in (either as the guest
public user or otherwise).  Additionally, the About page no longer
automatically logs you in as the public user.  This keeps the login page
obtainable.
Note that this bit of JS is unnecessary
Remove code handled by the new menu callback and lifecycle configuration