Is it necessary to add a sub-module named "dp view" to present graphical results?

[panxiang126]

As the title suggests, I think this is a non-essential but user experience enhancing idea.

[panxiang126]

Concretely, matplotlib is called to plot the changes in key parameters after train, the error in energy & force and the distribution of force after test, etc.

[njzjz]

I prefer implementing this feature in a separate project.