data/map.htm: handle 180 < x < 360 in map MBR

The fix for #327 didn't switch longitudes for the MBR when the values
are 180 < x < 360.  Our services require -180 < x < 180.

Fixes #327

data/map.htm

@@ -132,6 +132,13 @@
       if(b._northEast.lng < -180) {
         b._northEast.lng += 360;
       }
+      // switch to negative longitudes if needed
+      if(b._southWest.lng > 180){
+        b._southWest.lng -= 360;
+      }
+      if(b._northEast.lng > 180){
+        b._northEast.lng -= 360;
+      }
       return [b._southWest.lng, b._northEast.lng, b._southWest.lat, b._northEast.lat];
      }
      return null;