Python 3.0 does not work with PL/Python

I have recently fixed the configure script to recognize Python 3.0.  But 
note that building and running PL/Python with Python 3.0 does not 
actually work.  It looks like several symbols have been removed or 
changed.  It would be good if the Python pundits around here could take 
a look.

(I have found Python 3.0 to be very quick and easy to install from 
source, in case your distribution doesn't have it packaged yet.)