patch removes dependencies on the old unsupported KoreanCodecs package
and the alternative JapaneseCodecs package.  Since both of those
provide aliases for their codecs, this removal just makes the generic
codec names work.

We needed to make slight changes to __init__() as well.

This will be backported to Python 2.3 when its branch freeze is over.

Charset: Alias __repr__ to __str__ for debugging.

header_encode(): When calling quopriMIME.header_encode(), set
maxlinelen=None so that the lower level function doesn't (also) try to
wrap/fold the line.

support and other charset defaults.  See also:

http://article.gmane.org/gmane.comp.python.mime.devel/250

(this just commits the last bit of the article that wasn't part of
email 2.4.3.)

#625509.  This isn't a huge problem because at the moment there are no
built-in charsets for which header_encoding is QP but body_encoding is
not.

which we know nothing else.

Korean, and Chinese codecs.

Coerce the argument to lower case.  Also, since body encodings can't
be SHORTEST, default the CHARSETS failobj's second item to BASE64.

encoding flag SHORTEST means to return the shortest encoding between
base64 and qp.  This is used for the header_enc for utf-8.  SHORTEST
isn't legal for body_enc.

Also some code cleanup:

- use True/False everywhere
- use == instead of `is' in a few places
- added _unicode() and make consistent the "is unicode" checks
- update docstrings

Python 2.1 compatibility.

Using Unicode-aware methods may still die with a NameError on unicode.
Maybe there's a more elegant solution but I doubt anybody cares.)

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 ;).