(rmail-summary-mode-map): Remove unneeded declaration.

(rmail-summary-mode-map): Remove unneeded declaration.
(top-level): No need for cl now.
(rmail-spam-filter, rmail-use-spam-filter, rsf-file, rsf-no-blind-cc)
(rsf-beep, rsf-sleep-after-message, rsf-min-region-to-spam-list)
(rsf-autosave-newly-added-definitions, rsf-white-list)
(rsf-definitions-alist, rsf-check-field, rsf-add-subject-to-spam-list)
(rsf-add-sender-to-spam-list, rsf-add-region-to-spam-list)
(rsf-customize-spam-definitions, rsf-customize-group)
(rsf-custom-save-all, rsf-add-content-type-field): Doc fixes.
(rsf-check-field): Use setcar and setcdr rather than setf.
(rmail-spam-filter): Simplify.
(rsf-add-subject-to-spam-list, rsf-add-sender-to-spam-list)
(rsf-add-region-to-spam-list): Use rmail-get-header or
buffer-substring-no-properties.  Regexp-quote the extracted data.
Make the messages less verbose.
(rmail-summary-mode-map, rmail-mode-map): Use easy-menu and dolist to
simplify things.
(rsf-add-content-type-field): Make the message less verbose.