Add the batch dimension to the input current as discussed in #306 Seems that the tutorial broke after a change in Torch, now the input current must have a batch dimension even when the dimension is 1, so I added a batch dimension to the input current in the tutorial 2 notebook and the tutorial 2 rst file.
Fix typo in the tutorial 2 rst file section 3.1, said "spk_in" instead of "cur_in"
All the other tutorials seem to still work okay.