Enhance train_eval_plot function

[CentofantiEze]

Enhance the train_eval_plot function.

To do list of desired behaviours:

• [x] Display training time.
• [ ] Plots
  • [ ] Generate data random example plot.
  • [x] Plot the training and validation losses.
  • [x] Plot the evolution of the Lipschitz constant.
  • [x] Plot the final forward-backwards parameters for each layer.
  • [x] Plot the evolution of the fb parameters.
  • [x] Plot one prediction for a signal in the dataset.
  • [ ] Plot the prediction for the gaussian curve.
• [x] Save results dictionary.