direction(dir) {
    this.settings.direction = dir || "ltr";

    if (this.manager) {
      this.manager.direction(this.settings.direction);
    }

    if (this.manager && this.manager.isRendered() && this.location) {
      this.manager.clear();
      this.display(this.location.start.cfi);
    }
  }
Adjust the direction of the rendition
@param  {string} dir