Remove some redundant `:group` args as well.
* lisp/mail/supercite.el: Use lexical-binding.
(completer-disable): Declare var.
(sc-set-variable): Don't rely on dynbind to access `help` variable.
* lisp/mail/mail-extr.el: Use lexical-binding.
(mail-extract-address-components): Avoid use of dynamic scoping to
refer to local vars.
* lisp/mail/mailabbrev.el: Use lexical-binding.
(mail-abbrev-make-syntax-table): Rename `_` variable to `syntax-_`.
* lisp/mail/mailheader.el: Use lexical-binding.
(headers): Don't declare as dynbound globally.
(mail-header-set, mail-header-merge): Declare `headers` as dynbound
locally, instead. Mark those functions as obsolete.
(mail-header-format): Use `alist-get` instead of `mail-header`.
* lisp/mail/binhex.el (binhex-decode-region-external): Remove always-nil
var `firstline`.
* lisp/mail/emacsbug.el: Use lexical-binding.
(report-emacs-bug): Remove always-nil var `message-end-point`.
* lisp/mail/rmail-spam-filter.el: Use lexical-binding.
(bbdb/mail_auto_create_p): Declare variable.
* lisp/mail/rmail.el (rmail-get-new-mail): Remove always-nil var
`delete-files`.
* lisp/mail/rmailout.el: Use lexical-binding.
(rmail-output-read-file-name): Remove unused var `err`.
(rmail-convert-to-babyl-format): Remove unused var `count`.
(rmail-output-as-mbox): Remove unused vars `from` and `date`.
* lisp/mail/rmailsort.el: Use lexical-binding.
(rmail-sort-messages): Remove unused var `msginfo`.
* lisp/mail/rfc822.el: Use lexical-binding.
* lisp/mail/rmailedit.el: Use lexical-binding.
* lisp/mail/mailclient.el: Use lexical-binding.
* lisp/mail/blessmail.el: Use lexical-binding.
* lisp/mail/mail-hist.el: Use lexical-binding.
* lisp/mail/rmailkwd.el: Use lexical-binding.
* lisp/mail/rmailmsc.el: Use lexical-binding.
* lisp/mail/uce.el: Use lexical-binding.
* lisp/mail/unrmail.el: Use lexical-binding.
Restore lines saying "Maintainer: emacs-devel@gnu.org" when there is
no special maintainer for a file. Although this wasn't documented
it was common practice and removing the lines didn't have consensus.
Most of this change is to boilerplate commentary such as license URLs.
This change was prompted by ftp://ftp.gnu.org's going-away party,
planned for November. Change these FTP URLs to https://ftp.gnu.org
instead. Make similar changes for URLs to other organizations moving
away from FTP. Also, change HTTP to HTTPS for URLs to gnu.org and
fsf.org when this works, as this will further help defend against
man-in-the-middle attacks (for this part I omitted the MS-DOS and
MS-Windows sources and the test tarballs to keep the workload down).
HTTPS is not fully working to lists.gnu.org so I left those URLs alone
for now.
