Update of RNN to get Pipeline of 1 and first try at LSTM.

Created by: violatingcp

Adding LSTM and update for RNN to get down to a pipeline interval of 1. Additionally keeping the previous static impelementation of the RNN that uses significantly less resources. For a comparison we have:

| Name | BRAM_18K| DSP48E| FF | LUT | Interval | |Simple RNN Static Loop 5 | 0| 0| 419| 378| Full(9) | |Simple RNN Loop 5 | 0| 0| 884| 1057| 1 |Simple RNN Static Loop 10 | 0| 0| 799| 638| Full | |Simple RNN Loop 10 | 0| 0| 1804| 2257| 1 |

Loop 10 denotes an RNN with 10 iterations.

First LSTM is a bit slower than RNN, but has many multiplications. The minimum Pipeline interval is currently 4. It would be nice to see if this can be brought down to 1. Also, we might want to consider a static one with the two states that get passed back and forth.