urbanDensity - save/load

modules/save.js

@@ -33,7 +33,8 @@ function getMapData() {
     mapName.value,
     +hideLabels.checked,
     stylePreset.value,
-    +rescaleLabels.checked
+    +rescaleLabels.checked,
+    urbanDensity
   ].join("|");
   const coords = JSON.stringify(mapCoordinates);
   const biomes = [biomesData.color, biomesData.habitability, biomesData.name].join("|");