Issue #15142: Fix reference leak when deallocating instances of types created using PyType_FromSpec().

Close #14857: fix regression in references to PEP 3135 implicit __class__ closure variable. Reopens issue #12370, but also updates unittest.mock to workaround that issue

This also alters the fix to #11603. Specifically, setting __repr__ to
object.__str__ now raises a recursion RuntimeError when str() or repr() is
called instead of silently bypassing the recursion. I believe this behavior is
more correct.

Patch from Mark Shannon.

These functions simplify the usage of static constant Unicode strings.
Generalize the usage of _Py_Identifier in ceval.c and typeobject.c.

the type MRO to avoid a crash if the MRO is changed during the lookup.

Patch from Armin, test from me.

dict anymore if the key is present. Reject also non-string qualified names.
And fix reference leaks in type.__new__().

I had to move the static identifier code from unicodeobject.h to object.h in
order for this to work.

Patch by sbt.

effect of appearing to resolve the issue.  Thanks to Mark Shannon for
noticing.

http://mail.python.org/pipermail/python-dev/2011-November/114347.html

Issue 1294232: Fix errors in metaclass calculation affecting some cases of metaclass inheritance. Patch by Daniel Urban.

Thanks to Konrad Schöbel and Jasper Schulz for helping with the mass-editing.