python PMCs

[Leopold Toetsch]

dynclasses/py*.pmc need some work. At the time Sam Ruby created these
PMCs, Parrot didn't provide all the semantics necessary to support
Python. This situation is by far better now but the transition of Parrot
internals isn't yet finished.

Anyway, the following issues are existing (at least):

* most if not all of the __methods__ have an extra C<self> argument in
addition to C<SELF> aka the invocant. This wrong implementation is also
tested - e.g. pyint.t:

$P2 = $P1.__abs__($P1)

* py*.pmc duplicates some Parrot API to run user code from C, e.g.
Parrot_PyClass_runops_fromc(). This is not only unneeded as Parrot
provides a bunch of functions to achieve that, it will also *break* in
the very near future.

The ongoing changes to calling conventions and context handling will
make it necessary to disable compiling py*.pmcs. See also ticket #36374
and the attached patch context_4.patch.

Sorry for the inconvinience,
leo