Merge changes made in Gnus trunk.

Merge changes made in Gnus trunk.

nnimap.el (nnimap-insert-partial-structure): Fix boundary detection.
spam.el (spam-list-of-processors): Mark as obsolete.
gnus-art.el (gnus-blocked-images): New function.  Allow the `gnus-blocked-images' to be a function.
gnus-art.el (gnus-article-wash-function): Remove it, and use `mm-text-html-renderer' instead.
mm-decode.el (mm-inline-text-html-renderer): Removed.
mm-decode.el (mm-inline-media-tests): Removed use.
mm-view.el (mm-inline-text-html): Removed use.
mm-view.el (mm-text-html-renderer-alist): Add the `shr' and `gnus-w3m' symbols.
gnus.texi (Article Washing): shr and gnus-w3m, not the direct function names.
gnus-art.el (article-wash-html): Simplify and remove the charset stuff.  Use the normal html rendering code instead of the special html washing code.
mm-view.el (mm-text-html-washer-alist): Removed.
gnus-news.texi: Mention that mm-text-html-renderer is the only HTML variable now.
shr.el (shr-tag-table): Remove useless nconc.