Add option to block to fix map dimensions to match the image dimensions and do not allow panning outside of image

[dutchigor]

Panning outside an image has to be possible with unknown map dimensions because otherwise the full image could never fit in one frame. However, if the map dimensions are fixed to the image dimensions, we could restrict the panning.

[daniela0321]

Should we also allow changing the map hight per device? Let's discuss this before working with this ticket.

Below an example where the hight is 800px which is good for desktop but not for mobile:

Or would it be possible to make the image scale based on the viewport size? What look good in my bigger screen, doesn't look good in my laptop screen (it cuts the image on the top), see below: