#15 change map tiles with different zoom levels

[Andrew Hitchcock]

Right now when you zoom out, it just makes the images smaller. This puts a heavy load on browsers because they must manage a whole bunch of small images, scale the images, and move them when you scroll.

It would be nice if we could create different levels of maps (pre-scaled and hosted on the server) so the downloads are faster and performance is better on slow machines. When a zoom level is changed, it would request the different scale images.

Also, some browsers do ugly scaling, so this would be a cosmetic fix as well.