Add support for 512px Mapbox Satellite tiles

The tiler and projection are still not aware of the 512px size.
This results in fetching 512px images but placing them in the 256px slippy map
and scalling them down.

(This is dumb but at least they look nicer than before)

modules/renderer/tile_layer.js

@@ -272,7 +272,8 @@ export function rendererTileLayer(context) {
         _source = _;
         _tileSize = _source.tileSize;
         _cache = {};
-        tiler.tileSize(_source.tileSize).zoomExtent(_source.zoomExtent);
+        // tiler.tileSize(_source.tileSize).zoomExtent(_source.zoomExtent);   // not yet
+        tiler.zoomExtent(_source.zoomExtent);
         return background;
     };