* Python/ceval.c, Include/ceval.h: promote MakePendingCalls to global: Py_MakePendingCalls. Also guard against recursive calls * Include/classobject.h, Objects/classobject.c, Python/{ceval.c,bltinmodule.c}: entirely redone operator overloading. The rules for class instances are now much more relaxed than for other built-in types (whose coerce must still return two objects of the same type)