Jochem 't Hart

@pvgenuchten The check for `tilejson` startswith 2 was there, because version 2 was not supported. However, I didn't realize that tilejson is not mandatory in all versions. I have now...

> @jochemthart1 thanx for checking the fact that level 14 is not available relates to the fact that [tilejson.json](https://tiles.isric.org/wosis.json) indicates that max-zoomlevel is 12.... Ah, the available zoom-levels are taken...