Introduction to rich comparisons:
Introduction to rich comparisons:

- Removed the nb_add slot from the PyNumberMethods struct.

- Renamed Py_TPFLAGS_NEWSTYLENUMBER to Py_TPFLAGS_CHECKTYPES.

- Added typedef richcmpfunc.

- Added tp_richcompare slot to PyTypeObject (replacing spare tp_xxx7).

- Added APIs PyObject_RichCompare() and PyObject_RichCompareBool().

- Added rich comparison operators Py_LT through Py_GE.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator