Inclusion of ANN method

[ggurioli]

Last commit with files: Inclusion of ANN method 669c7cd

[ndem0]

I think the optimizer should be passed in the init (as you did for the loss for example)

Right now it is not trivial as for the loss: the optimizer has to be constructed passing the model parameters, which means:

• we can pass the class instead the instance, but the optimizer arguments are then the default ones (or you have to create a new class with the wanted parameters)
• we can pass a dictionary with the optimizer class and all the arguments.

I prefer the second option, we plan to insert something like that in future