* Once MoveJobs work, enable and test moving to sent-mail.  Here is why it
  doesn't work currently: Akonadi::Monitor sends itemMoved(...), but it is
  not handled in AgentBase::Observer, and so it never gets "processed", and
  is stuck in the Monitor/ChangeRecorder forever.  (I.e. the resource will
  not get any new notifications.) This has to be fixed in Akonadi, but that
  means adding ObserverV2 or something.
* Figure out which / whether error strings should be i18n'd
* Should probably use progressMessage instead of statusMessage, but it seems
  to be unimplemented in AgentInstance, and only a stub in AgentBase.
* Do something about timeouts.
* Test aborting and progress reporting for resource-based transports.

Bugs:
* Incorrect size reporting in itemChanged() from Monitor.  Leads to displaying
  >100% progress.
  (found with: offline, queue some, online, abort, clearerror)
