should just be "getset", not "getset.__init__".

into a hardcoded char* buffer.

Closes patch #454743.

the delete function.  (Question: should the attribute name also be
recorded in the getset object?  That makes the protocol more work, but
may give us better error messages.)

with a NULL value), in a somewhat lame way: call the set() function
with one argument.  Should I add a 3rd function, 'del', instead?

getset_doc: add docstring.

This implements the 'getset' class from test_binop.py.

- descrobject.c:descr_check(): only believe None means the same as
  NULL if the type given is None's type.

- typeobject.c:wrap_descr_get(): don't "conventiently" default an
  absent type to the type of the object argument.  Let the called
  function figure it out.