Quoting fixes in Gnus

Quoting fixes in Gnus

* lisp/gnus/gnus-agent.el:
(gnus-agent-possibly-synchronize-flags-server):
* lisp/gnus/gnus-art.el (gnus-article-browse-delete-temp-files):
* lisp/gnus/gnus-eform.el (gnus-edit-form):
* lisp/gnus/gnus-group.el (gnus-group-edit-group)
(gnus-group-nnimap-edit-acl):
* lisp/gnus/gnus-topic.el (gnus-topic-edit-parameters):
* lisp/gnus/mail-source.el (mail-source-delete-old-incoming):
* lisp/gnus/message.el (message-strip-subject-encoded-words)
(message-check-recipients, message-send-form-letter):
* lisp/gnus/mm-decode.el (mm-display-part):
* lisp/gnus/mm-uu.el (mm-uu-pgp-signed-extract-1):
* lisp/gnus/mml-smime.el (mml-smime-get-dns-cert)
(mml-smime-get-ldap-cert):
* lisp/gnus/spam-report.el (spam-report-process-queue):
Respect ‘text-quoting-style’ in diagnostics.
* lisp/gnus/gnus-art.el (article-display-face)
* lisp/gnus/gnus-fun.el (gnus-display-x-face-in-from):
Use straight quoting in email.
* lisp/gnus/rfc2231.el (rfc2231-decode-encoded-string):
Escape apostrophes in doc strings.