[LSTM] with and without output gate option

Some paper run experiment on LSTM on case with and without output gate.

For example, this paper Towards Universal Paraphrastic Sentence Embeddings table 5 in section 4.4.

I would like to suggest an option to turn on/off output gate.

Usually for any modification of the default LSTM module, we suggest that you write your own custom LSTM using nn.LSTMCell for example.