Trainer Tutorial (#271)

* adding tutorial trainer
* implementing deepcopy for AbstractProblem and LabelTensor to match Lightning Callbacks

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Co-authored-by: Dario Coscia <dariocoscia@Dario-Coscia.local>

tutorials/README.md

@@ -7,6 +7,7 @@ In this folder we collect useful tutorials in order to understand the principles
 | Description   | Tutorial |
 |---------------|-----------|
 Introduction to PINA for Physics Informed Neural Networks training|[[.ipynb](tutorial1/tutorial.ipynb), [.py](tutorial1/tutorial.py), [.html](http://mathlab.github.io/PINA/_rst/tutorials/tutorial1/tutorial.html)]|
+PINA and PyTorch Lightning, training tips and visualizations|[[.ipynb](tutorial11/tutorial.ipynb), [.py](tutorial11/tutorial.py), [.html](http://mathlab.github.io/PINA/_rst/tutorials/tutorial11/tutorial.html)]|
 Building custom geometries with PINA `Location` class|[[.ipynb](tutorial6/tutorial.ipynb), [.py](tutorial6/tutorial.py), [.html](http://mathlab.github.io/PINA/_rst/tutorials/tutorial6/tutorial.html)]|