folding. Note that some of the Japanese tests have changed, but I
don't really know if they are correct or not. :(
Someone with Japanese and RFC 2047 expertise, please take a look!
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 ;).