Adapt the garbage collection tests to run under PyPy. This makes the overall test diff smaller and easier to read.

Fix the last doctest errors in pure-python mode about parent circles. They were another manifestation of zopefoundation/ExtensionClass#3 and required a workaround.

Add tests for all the methods proxied by the C wrappers, and make the Python implementation match that behaviour.

All tests continue to pass under 2.6 and 2.7.

The pure-python code currently raises AttributeError instead of RuntimeError in the
recursive-parent cases, though I'm not sure why that is. There may also be some issues
with the proxying of some methods, but those aren't covered by current test cases.

setup.py: Set url to github

See: http://blog.travis-ci.com/2014-12-17-faster-builds-with-container-based-infrastructure/

Only in ASCII encoding.

Fixes LP #143358.

README.rst in root, w/ prolog.

CHANGES.rst in foot.

Fixes LP #1387363.

LP #1155760.

Give up on protecting against segfaults in aq_* functions, when we encounter __parent__ circles with more than one intermediate object.

Raise `RuntimeError: Recursion detected in acquisition wrapper` if an object with a `__parent__` pointer points to a wrapper that in turn points to the original object.