[Distutils] Final PEP 241 patch

[A.M. Kuchling]

After two long-distance calls to Montreal and another hour of work,
I've uploaded a new version of the PEP 241 patch that is ready to go
in.  Can some please review it for me before I check it in (on
Wednesday, I hope).

Final questions:  

   * When the 'platforms' argument isn't specified, the option will be
set to ['UNKNOWN'], not an empty list.  Is that OK?  The keywords
argument, if not specified, will be treated as an empty list, which
does seem the obviously correct thing to do.

   * 'Author' in the metadata comes from the maintainer fields, my
argument here being that, if they're different, the catalog is only
interested in who maintains the package *now*, not whoever wrote it
originally.  Is that OK?  Adding a maintainer field to the metadata,
thus preserving the author/maintainer division, would be trivial.
I'll bow to cataloguers; if it would be useful, let me know and I'll
add it.

--amk