Adding parameters to optimizer automatically

[LarsSchaaf]

#525

Current Behaviour
If a new parameter is added to the model, the parameters dont get trained. This is because currently only certain parameters are explicitly added to the optimiser. This is done to be able to add different weight decays for specific parameters.

Desired behaviour
When developing and adding new Modules with new parameters one expects these to be trained during training. Hence a function that automatically adds any parameters that don't have explicit optimisation parameters defined to be added to the optimiser with default settings.

Alternatives
Printing a warning

[ilyes319]

@LarsSchaaf Great thank you. I would move the function to script utils though: add_all_parameters_to_optimizer