fix iteration proxying to pass `self` acquisition-wrapped into `__iter__` and `__getitem__` (fixes https://bugs.launchpad.net/zope2/+bug/360761)

first add [https://bugs.launchpad.net/zope2/+bug/360761/comments/7 the tests] kindly provided by Tres

Define a FORMAT_N macro and use it wherever a python int needs to be built from a Py_ssize_t variable

Most likely this is not the only 'i' -> 'n' fix required.

o See http://www.python.org/dev/peps/pep-0353/ for details.

update for r94905: the proxy for `__iter__` must not rely on the object to have an `__iter__` itself, but also support fall-back iteration via `__getitem__` (this fixes https://bugs.launchpad.net/zope2/+bug/360761)

the package itself and make it a doctest.

http://www.zope.org/Documentation/Books/ZDG/current/Acquisition.stx

Clenaup