Add retina parameter to url template.

Closes #3404743

leaflet_more_maps.module

@@ -81,7 +81,7 @@ function _leaflet_more_maps_assemble_default_map_info(array &$map_info, array $d
   $prot = '//';
 
   // As used by most.
-  $zxy = '{z}/{x}/{y}.png';
+  $zxy = '{z}/{x}/{y}{r}.png';
   // As used by Esri.
   $zyx = '{z}/{y}/{x}.png';