feature/img-generation-per-n-round

[adradr]

Would be great to allow image generation only every n round to speed up the simulation.

Another approach would be to simply store the pixel grids for each step and generate the animation only at the very end of the simulation without storing every individual step's image. Therefore saving storage cost. This may require some kind of dumping of this growing array of grid data, so RAM use won't increase through the simulation.