module-level aq_acquire, aq_inner, aq_parent, etc. functions.

function so that we can write a module-level function for that functionality
as well.

Log message for revision 71227:
  Step 4: Make aq_get aware of __parent__ pointers.
  (Also some comment cosmetics in _Acquisition.c)

Log message for revision 71228:
  Test aq_parent property as well (in addition to aq_parent function)

Log message for revision 71229:
  Step 5: Make aq_chain aware of __parent__ pointers.

Log message for revision 71224:
  Step 3: Make aq_parent aware of __parent__ pointers.

Log message for revision 71221:
  Step 2: Make aq_acquire aware of __parent__ pointers, even if the object
  isn't acquisition wrapped.

Log message for revision 71223:
  Add another test that tests acquisition wrappers with containers that have __parent__.

Log message for revision 71225:
  Cosmetics: adjust a piece of code that I added earlier to the indentation
  style of the overall file

Log message for revision 71226:
  Cleanup:
  * no need to introduce another variable where we check for a __parent__ attribute
  * clean up after failed getattr (it throws an AttributeError)
  * properly DECREF the __parent__ attribute when it's no longer needed and
    the wrapper that is temporarily created from the __parent__ attribute.

Log message for revision 75578:
  Added a test to Acquisition that shows the current segmentation fault problem, when Acquisition goes in circles.

Log message for revision 76140:
  First attempt to fix 'Acquisition problem' when encountering cyclic hierarchies via __parent__ pointers. [hannosch, nouri]


In addition, Hanno and Nouri's fix was expanded to not only cover circular __parent__
pointers but also to cover a mixture of circular __parent__ and aq_parent pointers
(which can occur when old Implicit acquisition meets new __parent__ pointer code).

Also cleaned up much of the comments and added more comments.

  Allow assignment to a wrapper's __parent__.

  Warming up: Make acquisition wrappers have __parent__ in addition to aq_parent
  (they point to the same thing).