[Feature] Make the maximum zoom amount configurable

[Igggosha]

The main advantage of the web map is that it allows to zoom out further, but still not more than around 2 thousand by 3 thousand blocks which is pretty badly low, even though it is better than the fullscreen map.
I believe that making it configurable for the user in the settings, or at least putting it in a json file in the clientside portion of the map, would greatly benefit the usefulness of the map.