Add `recurrent_dropout` option to `BaseRecurrentLayer`. Following either (or both) of https://arxiv.org/abs/1603.05118, https://arxiv.org/abs/1512.05287
Add
recurrent_dropoutoption toBaseRecurrentLayer. Following either (or both) of https://arxiv.org/abs/1603.05118, https://arxiv.org/abs/1512.05287