[Feature Request] Support batch processing for predictSoftly

[LostMekka]

Sequential.predictSoftly should also have a batch version, similar to Sequential.predict.

This came up in #25:

c.)
There should be a means to call predictSoftly on a batch of inputs. At the moment this is only possible for predict.

That would be awesome as well. My current pet project to try out this library is a board game AI that very crudely learns through self play, where the neural net is the search heuristic. The AI plays a semi-random game sequence and for each pair of successive moves I create a training data point. (needs 1 predictSoftly per data point) Building these self-play datasets would probably greatly benefit from batch soft-predicting 😄

Originally posted by @LostMekka in #25 (comment)