*   Change the state_size order of the StackedRNNCell to be natural order.
        To keep the existing behavior, user can add reverse_state_order=True
        when constructing the StackedRNNCells.
    *   Deprecate self.test_session() in favor of self.session() or
        self.cached_session().
    *   Directly import tensor.proto.h (the transitive import will be removed
        from tensor.h soon).