Add resolution based on zoom levels

[Falke-Design]

This feature makes it possible that the GeoTIFF is rendered differently based on the zoom level. This has the benefit, that we have a much better performance while moving the map and still having a high resolution on a high zoom level.

Example:
Resolution from zoom level 0 and higher is 32, if zoom is 10 or higher the resolution is 100 and from 18 and higher it is 200.

var layer = new GeoRasterLayer({
    georaster: georaster,
    resolution: {
        0: 32,
        10: 100,
        18: 200
    }
});

[DanielJDufour]

Awesome! I think it would be nice to have a test added to this folder: https://github.com/GeoTIFF/georaster-layer-for-leaflet/tree/master/tests

Would you be interested in writing one? If not, I'd be happy to write one. I'm really appreciative of all the work you've put in and don't mean to add boring work.

[DanielJDufour]

In either case, we can take that up in a subsequent PR :-)

[Falke-Design]

Would you be interested in writing one? If not, I'd be happy to write one. I'm really appreciative of all the work you've put in and don't mean to add boring work.

I will create one 👍