Make start zoom level and tile coordinate driven by template url
Make start zoom level and tile coordinate driven by template url

Fetching will start from the tile given in the url and move right
and down to fill up a full viewport, then move to next zoom level
and re-adapt starting X and Y too

wsw0108/Windshaft,CartoDB/Windshaft,manueltimita/Windshaft,CartoDB/Windshaft,wsw0108/Windshaft,manueltimita/Windshaft,CartoDB/Windshaft,HydroLogic/Windshaft,wsw0108/Windshaft,HydroLogic/Windshaft,manueltimita/Windshaft,HydroLogic/Windshaft