Added logic so:  Missing.Value.spam() returns Missing.Value.
Added logic to make Missing.Value picklable.

the same interface as send, but uses the schedular to send message
instead of calling the SendMail class directly.

This thing needs an overhaul; already. :-(

no longer uses ml.

in the management process.

 - header handling (now handles multi-line again)
 - an minor typo in the __del__ action for SendMail
   (the class that actually communicates the SMTP)