Added cached map thumbnail from tmio (closes #73)

src/structures/TMMap.js

@@ -61,6 +61,14 @@ class TMMap {
         return this._data.mapUid;
     }
 
+    /**
+     * The map Storage Object ID.
+     * @returns {string}
+     */
+    get storageId() {
+        return this.thumbnail.replace(/^[a-z:/.]*([^]*)\.[a-z]*$/gi, '$1');
+    }
+
     /**
      * The map author.
      * @returns {Promise<Player>}
@@ -115,13 +123,21 @@ class TMMap {
     }
 
     /**
-     * The map thumbnail.
+     * The map thumbnail (from Nadeo services, direct download).
      * @type {string}
      */
     get thumbnail() {
         return this._data.thumbnailUrl;
     }
 
+    /**
+     * The map thumbnail (cached from trackmania.io, can show).
+     * @type {string}
+     */
+    get thumbnailCached() {
+        return `${new ReqUtil(this.client).tmioAPIURL}/download/jpg/${this.storageId}`;
+    }
+
     /**
      * The map exchange id, if the map is on trackmania.exchange, else null.
      * @type {?string}