Fix for bug in plpython bool type conversion

Hi!

The attached patch fixes a bug in plpython.

This bug was found while creating sql from trigger functions
written in plpython and later running the generated sql.
The problem was that boolean was was silently converted to
integer, which is ok for python but fails when the created
sql is used.

The patch uses the Py_RETURN_xxx macros shown at
http://docs.python.org/api/boolObjects.html .

It would be nice if someone could test and comment
on the patch.

Cheers
Guido