* Add error checking code to PyList_Append() call.

* Replace PyObject_CallMethod(to->outbasket, "pop", NULL) with equivalent
  in-line code.  Inlining is important here because the search for the
  pop method will occur for every element returned by the iterator.

* Make tee's dealloc() a little smarter.  If the trailing iterator is
  being deallocated, then the queue data is no longer needed and can
  be freed.