Add optional docstrings to member descriptors.  For backwards
compatibility, this required all places where an array of "struct
memberlist" structures was declared that is referenced from a type's
tp_members slot to change the type of the structure to PyMemberDef;
"struct memberlist" is now only used by old code that still calls
PyMember_Get/Set.  The code in PyObject_GenericGetAttr/SetAttr now
calls the new APIs PyMember_GetOne/SetOne, which take a PyMemberDef
argument.

As examples, I added actual docstrings to the attributes of a few
types: file, complex, instance method, super, and xxsubtype.spamlist.

Also converted the symtable to new style getattr.
diff --git a/Include/object.h b/Include/object.h
index 160331e..1d0ae5f 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -274,7 +274,7 @@
 
 	/* Attribute descriptor and subclassing stuff */
 	struct PyMethodDef *tp_methods;
-	struct memberlist *tp_members;
+	struct PyMemberDef *tp_members;
 	struct getsetlist *tp_getset;
 	struct _typeobject *tp_base;
 	PyObject *tp_dict;