Elman Recurrent Neural Networks with Back-propagation-through-time (BPTT)
Based from: Werbos, Paul J. "Backpropagation through time: what it does and how to do it." Proceedings of the IEEE 78.10 (1990): 1550-1560.
https://en.wikipedia.org/wiki/Backpropagation_through_time
based from: https://github.com/rohitash-chandra/feedforward-neural-network
used in: https://github.com/rohitash-chandra/CooperativeCoevolution-RNN