Take a look and see what you think. The map and the sprites are re-scale...

...d appropriately depending on the window resizing. However, the map remains centered if ONLY the window is vertically resized or ONLY if the window is horizontally resized. When the window is resized in both directions, the map is almost but not quite centered. If there are any obvious errs that I've made, let me know, otherwise I can show everyone what it's doing when we meet on Sunday.

I'm creating a pull request for this in case anyone wanted to test this branch for themselves. I think you would be able to do that without a pull request but I wasn't positive.