testrunner.py otherwise buffers output inside my eshell sessions.

the code was using ex=sys.exc_info() instead of ex=sys.exc_info()[1];
only shows up when sqlite3 is not installed.

cythonpp.py: copy implementations of itertools.combinations() and itertools.product(). This fixes cythonpp.py on python 2.5.

itertools.combinations on snow leopard's python 2.6.1 raises a
ValueError instead of returning an empty iterator.

stupid setuptools creates a pure python load for ares.so. this makes
test__execmodules.py work again.

the following environ variables are now supported:
 - GEVENT_LOOP
 - GEVENT_RESOLVER
 - GEVENT_THREADPOOL
 - GEVENT_BACKEND