Merge changes made in Gnus trunk.

Merge changes made in Gnus trunk.

nnimap.el (nnimap-wait-for-response): If the user hits `C-g', kill the process, too.
nnir.el (gnus-summary-nnir-goto-thread): Modify to work with imap.
nnimap.el (nnimap-update-info): If the server doesn't return any useful info, just use the previous info.
nnimap.el (nnimap-update-info): Prefer old info over start-article.
nnimap.el (nnimap-update-qresync-info): Finish implementing QRESYNC.
auth-source.el (auth-source-create): Use (user-login-name) for the user name default.
nnimap.el (nnimap-open-connection): Use gnutls STARTTLS, if available.
nnimap.el (nnimap-update-info): Rely more on the current active than the param active to avoid marking articles as read too much.
gnus-sum.el (gnus-summary-set-local-parameters): Ignore the `active' non-variable, too.
nnimap.el (nnimap-update-qresync-info): \Flagged messages are read for Gnus.
nnimap.el (nnimap-retrieve-group-data-early): utf7-encode the group parameters.
nnimap.el (nnimap-update-qresync-info): Mark \Seen articles as read.