* gnus-group.el (): Require gnus-sum and autoload functions to
resolve warnings when gnus-group.el compiled alone.
(gnus-group-line-format): Documented new %F
(size of Fetched data) group line format; identifies disk space
used by agent and cache.
(gnus-group-line-format-alist): Defined new F format.
(gnus-total-fetched-for): New function.
(gnus-group-delete-group): No longer update
gnus-cache-active-altered as gnus-request-delete-group now keeps
the cache in sync.
(gnus-group-list-active): Let the agent store a server's active
list if currently plugged.