792a5142cd
need to first construct an instance with nulls. Also added newTuple(). Opted not to make newStreamableTuple() as that would make more sense in a Tuples class, but this method can only be accessed by calling StreamableTuple.newTuple which seems to me to already tell the whole story. git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5556 542714f4-19e9-0310-aa3c-eee0fc999fb1