Let me comment that as an author of the library. There are a few reasons actually. First, as mentioned it was biased to spectral methods from the very beginning

Let me comment that as an author of the library. There are a few reasons actually. First, as mentioned it was biased to spectral methods from the very beginning. Second reason is that I didn't even know how to implement and train neural nets properly. And the last reason why it is not here yet - unfortunately I don't have much time to implement that yet so contributions are welcome :)