Completely get rid of PyClass and PyInstance.

(classobject.[ch] aren't empty yet because they also define PyMethod.)
This breaks lots of stuff, notably cPickle. But it's a step in the right
direction. I'll clean it up later.
(Also a few unrelated changes, e.g. T_NONE to define a "struct member"
that is always None, and simplification of __hash__ -- these are unfinished.)

Objects/listobject.c

@@ -2381,13 +2381,6 @@ list_init(PyListObject *self, PyObject *args, PyObject *kw)
 	return 0;
 }
 
-static long
-list_nohash(PyObject *self)
-{
-	PyErr_SetString(PyExc_TypeError, "list objects are unhashable");
-	return -1;
-}
-
 static PyObject *list_iter(PyObject *seq);
 static PyObject *list_reversed(PyListObject* seq, PyObject* unused);
 
@@ -2655,7 +2648,7 @@ PyTypeObject PyList_Type = {
 	0,					/* tp_as_number */
 	&list_as_sequence,			/* tp_as_sequence */
 	&list_as_mapping,			/* tp_as_mapping */
-	list_nohash,				/* tp_hash */
+	0,					/* tp_hash */
 	0,					/* tp_call */
 	0,					/* tp_str */
 	PyObject_GenericGetAttr,		/* tp_getattro */