* Add a stub for the -confirm email command
* Add stubs for -leave and -unsubscribe
* Remove the crufty (and broken) 'tojoin' 'toleave' and 'toconfirm' metadata
  keys for synchronizing between lmtp and the command runner.  Replace this by
  putting the subaddress recognized by lmtp into the metadata and having the
  command runner look at the subaddress.