Save image rendered with --display

[MathiasMehl]

Maybe allow user to choose to save the image or not.
Save only the latest image overwriting previous iamges, perhaps name it netFile-statsFile so that it is easy to identify the files used to generate it.

[falkecarlsen]

A more simple twist to this could be to simply always save the file in the naming scheme you mentioned. A user must then move the image if they wish to preserve it, otherwise it will be overwritten. Tacking on sequential numbers could also be an option.

Preferably these files should be stored in a maps/images folder to prevent clutter - especially with sequential numbering.