NNTPError - derived from Exception, it's the base class for all
    other exceptions in this module

    NNTPReplyError - what used to be error_reply

    NNTPTemporaryError - what used to be error_temp

    NNTPPermanentError - what used to be error_perm

    NNTPProtocolError - what used to be error_proto

    NNTPDataError - what used to be error_data

All the old names are retained for backwards compatibility; they point
to the class that replaces them.  Also, any code in this module that
raises an exception, now does so with the exception class.

NNTP.__init__(): Added a new optional argument `readermode', which is
a flag that defaults to false.  When set to true, the "mode reader"
command is sent to the NNTP server before user authentication.  Reader
mode is sometimes necessary if you are connecting to an NNTP server on
the local machine and intend to call reader-specific comamnds, such as
`group'.  If you get unexpected NNTPPermanentErrors, you might need to
set readermode.  Patch provided by Thomas Wouters (who include the
standard disclaimer on is patches@python.org submission), and inspired
by Jim Tittsler.