Many fixes, now it's working well
Many fixes, now it's working well

* Adapted the code to use owl_mini.png
* Rename loadIronman() to default() image (more accurate)
* Conv2d sobel and identity filter must not be detached, they are cutting the backpropagation otherwise
* Gradients are normalized preventing the gradients to explode (typical problem in RNN, LSTM... time series)
* Range of growing steps are calculated from grid dimensions
samuxiii/prototypes,samuxiii/prototypes