Update to Submit RFC

RFC 2476 needs an update.  On my short list are:

1. Need to adjust the mandatory wait times for SMTP command responses down
   to reasonable numbers for submission.

2. Make SMTP AUTH (RFC 2554) a MUST.

3. Make STARTTLS + SASL PLAIN (RFC 3207, RFC 2595) the mandatory
   to implement authentication mechanism.

4. Make 8BITMIME a MUST.

5. Update references where appropriate.

Objections?  Any more items for the list?  Randy, do you have any cycles to
work on 2476bis?

                - Chris