Add iconURL/avatarURL and fix object.values reference

src/structures/User.js

@@ -1,4 +1,5 @@
 const TextBasedChannel = require('./interface/TextBasedChannel');
+const Constants = require('../util/Constants');
 
 /**
  * Represents a User on Discord.
@@ -65,6 +66,18 @@ class User {
     return `<@${this.id}>`;
   }
 
+  /**
+   * A link to the user's avatar (if they have one, otherwise null)
+   * @type {?String}
+   * @readonly
+   */
+  get avatarURL() {
+    if (!this.avatar) {
+      return null;
+    }
+    return Constants.Endpoints.avatar(this.id, this.avatar);
+  }
+
   /**
    * Deletes a DM Channel (if one exists) between the Client and the User. Resolves with the Channel if successful.
    * @return {Promise<DMChannel>}