Always show mbtiles map layer, regardless of zoom

[ahblake]

I was about to reply and tell you that different basemaps do different things when you zoom past the highest level in your tileset

I found this a while back when the mapbox update removed the ability to zoom very very close

@ahblake

Mapbox will pixellate the highest zoom level in the tileset (eg 0-20 tileset, pixellate 20 as you zoom to 21, 22), but USGS, OSM, Carto, Stamen will hide the tileset and show the underlying basemap.