[Python-3000] New io system and binary data

["Martin v. Löwis"]

> The problem here seems to be that this isn't currently well documented.  
> I've got no objection to using the buffer attribute...

Ok, then it seems you missed the obvious way: Open the file in binary
mode ('rb' or 'wb') if you want to read or write bytes. It has always
been that way in Python; the only change now is that it matters on
systems other than Windows.

Regards,
Martin