Restrict photo.giveNearestPhotos distance

Since nearSpehre is costly on big distances, especially in low points
density areas, it is reasonable to make it 10km by default, It is used
in Nearest Photos feed in photo view which does not require very distant
photo to show for the price of slow Mongo response.  Method was also in
API use, we restrict max distance to 1000km for the same reason.

controllers/photo.js

@@ -1936,7 +1936,7 @@ async function giveUserPhotosAround({ cid, limitL, limitR }) {
  * @param {number} obj.year
  * @param {number} obj.year2
  * @param {number} obj.except cid to exclude
- * @param {number} obj.distance distance in radians
+ * @param {number} obj.distance distance in meters (1000km max)
  * @param {number} obj.limit
  * @param {number} obj.skip
  * @returns {object[]} photos
@@ -1977,11 +1977,11 @@ async function giveNearestPhotos({ geo, type, year, year2, except, distance, lim
         query.cid = { $ne: except };
     }
 
-    if (_.isNumber(distance) && distance > 0 && distance < Math.PI) {
-        query.geo.$nearSphere.$maxDistance = Utils.geo.rad2meter(distance);
+    if (_.isNumber(distance) && distance > 0) {
+        query.geo.$nearSphere.$maxDistance = Math.min(1000000, distance);
     } else {
-        // By default restrict distance to hemisphere with the center at the point.
-        query.geo.$nearSphere.$maxDistance = Utils.geo.rad2meter(Math.PI / 2);
+        // By default restrict distance to 10km.
+        query.geo.$nearSphere.$maxDistance = 10000;
     }
 
     if (_.isNumber(limit) && limit > 0 && limit < 30) {