* lisp/gnus.el (toplevel): Add autoloads for

* lisp/gnus.el (toplevel): Add autoloads for
`gnus-namazu-create-index', and `gnus-namazu-update-all-indices'
and `gnus-namazu-update-index'.

* lisp/gnus-namazu.el: Support automatically updating multiple
indices.
(gnus-namazu-make-index-interval): Abolished.
(gnus-namazu-index-update-interval): New option.
(gnus-namazu/setup): Call `gnus-namazu-update-all-indices' instead
of `gnus-namazu-make-index'.
(gnus-namazu/mknmz-process): Abolished.
(gnus-namazu/status-file-name): New macro.
(gnus-namazu-make-index, gnus-namazu-make-index-stop,
gnus-namazu/mknmz-sentinel): Removed.
(gnus-namazu/mknmz-cleanup, gnus-namazu/index-old-p): New function.
(gnus-namazu-create-index, gnus-namazu-update-all-indices,
gnus-namazu-update-index, gnus-namazu-stop-update): New command.
(gnus-namazu/update-directories, gnus-namazu/update-process): New
internal variable.