Modify requires and evals to reduce byte compilation warnings.

Modify requires and evals to reduce byte compilation warnings.

(rmail-ignored-headers): Ignore "from" but not "mail-from".  Ignore
"x-authentication-warning", "x-operating-system", and new babyl-V6
headers.

(rmail-displayed-headers): Add basic headers.

(rmail-message-vector, rmail-deleted-vector, rmail-msgref-vector,
rmail-convert-file): Deprecated.

(rmail-unix-mail-delimiter): Updated comment, anchored the "From"
string to the beginning of the line.

(rmail): Do not convert the buffer to Babyl format; Add support for
initializing and getting mbox format mail

(rmail-insert-rmail-file-header): Replace the Babyl identifier text
with an X-BABYL mail header.

(rmail-initialize-message): New function.

(rmail-url-map): Use "B" to send a mail message body to a browser; Map
"j" to (rmail-message) rather than (rmail-show-message); Map "o" to
(rmail-output) rather than (rmail-output-to-rmail-file); Add support
for handling embedded URLs.

(rmail-mode-map): Map the "Output (inbox)" menubar item to use
rmail-output.

(rmail-revert): Do not convert to Babyl 5 format; Use the new
initialization function.

(rmail-expunge-and-save): Use (rmail-display-summary-maybe).

(rmail-display-summary-maybe): New function.

(rmail-duplicate-message): Use the new rmail message descriptor to
access the message start and end positions.

(rmail-construct-io-menu): Use (rmail-output) instead of
(rmail-output-to-rmail-file).

(rmail-get-new-mail): Do not do a partial initialization; add a local
variable: 'current-message'; remove local variable 'success'; overhaul
the Babyl 5 specific parts.

(rmail-msg-is-pruned): Rewrite using the rmail message descriptor.

(rmail-toggle-header): Complete rewrite.

(rmail-narrow-to-non-pruned-header): Use the rmail message descriptor.

(rmail-display-labels, rmail-set-attribute): Rewrite.

(rmail-widen-to-current-msgbeg): Use the rmail message descriptor.

(rmail-process-new-messages): New (refactored) method.

(rmail-show-message): Rewrite.

(rmail-redecode-body): Rewrite using rmail message descriptor.

(rmail-auto-file): Make a little clearer; user (rmail-output) instead
of (rmail-output-to-rmail-file).

(rmail-next-undeleted-message): Slight rewrite.

(rmail-first-message, rmail-last-message, rmail-search-last-regexp):
Do not do partial initialization.

(rmail-what-message, rmail-search-message, rmail-message-regexp-p,
rmail-narrow-to-header): Use the rmail message descriptor.

(rmail-first-unseen-message, rmail-next-same-subject): Rewrite.

(rmail-message-deleted-p, rmail-delete-message,
rmail-undelete-previous-message, rmail-delete-forward, rmail-forward):
Use the rmail message descriptor.

(rmail-only-expunge, rmail-expunge): Rewrite.

(rmail-reply): Rewrite.

(rmail-narrow-to-message): New function.

(rmail-activate-urls, rmail-visit-url-at-mouse,
rmail-visit-url-at-point, rmail-browse-body, rmail-get-sender): New
functions.