Merge changes made in Gnus trunk.

Merge changes made in Gnus trunk.

gnus-group.el (gnus-group-line-format-alist): Have the ?U (unseen) spec inserr "*" if the group isn't active instead of 0.
nnimap.el (nnimap-request-create-group): Implement.
nnimap.el: Use the IMAP version of utf7-encode throughout.
nnimap.el: Implement the nnimap article expunging interface method, and make it more general.
gnus-group.el: Put back the nnimap autoloads needed to do the acl stuff.
gnus-sum.el (gnus-summary-move-article): When respooling to the same method, this would bug out.
nnimap.el (nnimap-request-group): When we have zero articles, return the right data to Gnus.
nnimap.el (nnimap-request-expire-articles): Only delete articles immediately if the target is 'delete.
nnmail.el (nnmail-expired-article-p): Allow returning the cutoff time for oldness in addition to being a predicate.
nnimap.el: Implement nnimap expiry.
nnimap.el (nnimap-request-move-article): Request the article before looking at what the Message-ID is.
nnimap.el (nnimap-mark-and-expunge-incoming): Wait for the last sequence.
gnus-sum.el (gnus-summary-move-article): Use gnus-server-equal to find out whether methods are equal.
nnimap.el (nnimap-find-expired-articles): Don't refer to nnml-inhibit-expiry.
nnmail.el (nnmail-expired-article-p): Fix typo: time-subtract.
gnus-start.el (gnus-get-unread-articles): Fix the prefixed select method in the presence of many similar methods.
When we have several similar methods, try to create as few extended methods as possible.
gnus-sum.el (gnus-adjust-marked-articles): Hack to avoid adjusting marks for nnimap, which is seldom the right thing to do.
gnus-int.el (gnus-open-server): Give a better error message in the "go offline" case.
gnus-sum.el (gnus-adjust-marked-articles): Fix another typo.
nnml.el (nnml-generate-nov-file): Fix variable name clobbering from previous patch.
gnus-start.el (gnus-get-unread-articles): Get the extended method slightly later to avoid double-getting it.