(rmail-update-summary): New function.

(rmail-update-summary): New function.
(rmail-new-summary): New arg redo-form.  Considerable rewrite
of how and when buffers are selected.
(rmail-summary-mode): New local vars rmail-summary-redo,
revert-buffer-function, post-command-hook, rmail-current-message.
(rmail-summary-expunge): Use rmail-update-summary.
(rmail-summary-get-new-mail): Likewise.
(rmail-summary-expunge-and-save): Likewise.
(rmail-summary-input): Don't update summary at all.
(rmail-summary-reply): Do the work inside save-window-excursion,
then switch to the mail buffer.
(rmail-summary-retry-failure): Likewise.
(rmail-summary-edit-current-message): Delete spurious autoload.
(rmail-summary-summary): Function deleted.
Use plain rmail-summary on h and C-M-h.
(rmail-summary-rmail-update): New function.

Big rewrite from weiner@pts.mot.com.