*   Remove `tf.contrib.data.Iterator.from_dataset()` method. Use
    `Dataset.make_initializable_iterator()` instead.
*   Remove seldom used and unnecessary `tf.contrib.data.Iterator.dispose_op()`.
*   Reorder some TF-GAN loss functions in a non-backwards compatible way.

## Known Issues

*   In Python 3, `Dataset.from_generator()` does not support Unicode strings.

non-nil, entries in this list can only be removed. Finalizers may be processed and removed in any order.  Order is NOT enforced because it introduces significant risk of stuck finalizers. finalizers is a shared field, any actor with permission can reorder it. If the finalizer list is processed in order, then this can lead to a situation in which the component responsible for the first finalizer in the list is waiting for a signal (field value, external system, or other) produced by a component responsible...

non-nil, entries in this list can only be removed. Finalizers may be processed and removed in any order.  Order is NOT enforced because it introduces significant risk of stuck finalizers. finalizers is a shared field, any actor with permission can reorder it. If the finalizer list is processed in order, then this can lead to a situation in which the component responsible for the first finalizer in the list is waiting for a signal (field value, external system, or other) produced by a component responsible...