code: function getAtlas(key) {
           if (typeof key === "string") {
             return this.atlases.get(key);
           } else {
             return this.atlases.values().next().value;
           }
         }
docs: return the default or specified atlas dictionnary
  @name getAtlas
  @memberOf me.Renderer.Texture
  @function
  @param {String} [name] atlas name in case of multipack textures
  @return {Object}