[PyGreSQL] DB API-2.0 + copy from stdin

[Christoph Zwerschke]

Thanks for the patch. I can polish that, add some tests and check it in.

Maybe we should check that the connection passed to DB is really a 
connection of the right class. We could then even pass it without the db 
keyword (i.e. if args[0] is a connection, use it).

@D'Arcy: What do you think? How about using only one underscore for the 
private attributes in pg? And how about public CVS read access?

-- Christoph