IMAPX: Remove unused member from GetMessageData struct.
CamelStore: Fix typo preventing valid folder renames.
CamelIMAPXServer: Fix handling of LSUB responses.

If we receive an LSUB response on a mailbox name but no corresponding
LIST response, ignore it.  IMAP allows subscriptions to mailbox names
regardless of whether the mailbox actually exists.  Not useful to us.
NEWS update for 3.11.3 release.
Post-release version bump.