Merge changes made in Gnus trunk

2013-02-13  Glenn Morris  <rgm@gnu.org>
* message.texi (News Headers): Don't mention yow any more.

2013-02-13  Juri Linkov  <juri@jurta.org>
* gnus-art.el (gnus-article-mode-map):
* gnus-sum.el (gnus-summary-mode-map, gnus-summary-article-map):
  Make S-SPC scroll in the opposite sense to SPC.  (Bug#2145)

2013-02-12  Paul Eggert  <eggert@cs.ucla.edu>
* gnus-group.el (gnus-group-browse-foreign-server):
* gnus-start.el (gnus-check-new-newsgroups):
* nnmail.el (nnmail-expiry-wait-function, nnmail-read-incoming-hook):
* smime.el (smime-crl-check):
* emacs-mime.texi (Charset Translation):
* gnus-faq.texi (FAQ 5 - Composing messages):
* gnus.texi (Group Levels, Exiting the Summary Buffer, Common Variables)
  (Agent and flags, Score File Format, The problem of spam)
  (Gnus Registry Setup, Oort Gnus, Terminology)
  (Optional Back End Functions):
* message.texi (Message Buffers):
* sieve.texi (Managing Sieve):
  In doc, use standard American English style for e.g., etc., i.e.
gnus-util.el (gnus-define-keys): Convert [?\S-\ ] to [(shift space)] for XEmacs
Generalize "animated" images to "multi-frame" images

shr.el (shr-put-image): Only animate images that specify a delay.
  This is consistent with the old image-animated-p behavior.
shr.el (shr-put-image): Use image-multi-frame-p if available
mml2015.el (mml2015-epg-find-usable-key): handle revoked user-id