Store images for dokumentation

[klanderfri]

Using the debug flag, one get the cards extracted and cropped, placed in folder, but with the limits drawn.
Having images of the cards, and only of the cards, would be good for future documentation of the cards. For example when selling the cards.

• Add a command argument for storing the card images in a certain map.
• Store the cropped images in that folder, but without the limit lines drawn.
• Add documentation about the functionality.