Message 80907 - Python tracker

Thanks for the review, Antoine.

Stage 2 applied to py3k in r69181, merged to 3.0 in r69182.

cmp, PyObject_Cmp and PyObject_Compare removed in r69184 (py3k) and r69185 
(release30-maint).

There's still the rename of the tp_compare slot to deal with, and a fair 
amount of cleaning up and documentation fixing to do.