Merge in D'Arcy Cain's python interface (PyGreSQL 2.0)

src/interfaces/python/Announce

src/interfaces/python/ChangeLog

src/interfaces/python/README

src/interfaces/python/pgext.py

src/interfaces/python/pgmodule.c

src/interfaces/python/tutorial/advanced.py

src/interfaces/python/tutorial/advanced.pyc

src/interfaces/python/tutorial/basics.py

src/interfaces/python/tutorial/func.py

src/interfaces/python/tutorial/func.pyc

src/interfaces/python/tutorial/pgtools.py

src/interfaces/python/tutorial/pgtools.pyc

src/interfaces/python/tutorial/syscat.py

src/interfaces/python/tutorial/syscat.pyc