Merge changes made in Gnus trunk.

Merge changes made in Gnus trunk.

gnus-gravatar.el (gnus-art): Required.
shr.el (shr-tag-img): Add align attribute support for <img>.
gnus-gravatar.el (gnus-gravatar-insert): Check if buffer is alive.
shr.el (shr-tag-img): Encode URL properly when retrieving.
shr.el (shr-get-image-data): Encode URL properly when fetching from cache.
shr.el (shr-tag-img): Use aligned-to spaces to align correctly images.
nnimap.el (nnimap-request-rename-group): Unselect by selecting a mailbox that doesn't exist.
rfc2231.el (rfc2231-parse-string): Ignore repeated parts.
gnus-gravatar.el (gnus-gravatar-too-ugly): Don't test if gnus-article-x-face-too-ugly is bound.