non-us-ascii character sets in headers and bodies. Some API changes
(with DeprecationWarnings for the old APIs). Better RFC-compliant
implementations of base64 and quoted-printable.
Updated test cases. Documentation updates to follow (after I finish
writing them ;).
Text.py and class Text => MIMEText.py and MIMEText
MessageRFC822.py and class MessageRFC822 => MIMEMessage.py and MIMEMessage
These are renamed so as to be more consistent; these are MIME specific
derived classes for when creating the object model out of whole cloth.