nextRender(callback, keep = false) {
        return this.renderer.nextRender.add(callback, keep);
    }
Executes a callback on next frame

     params:
     @callback (function): callback to execute on next frame
     @keep (bool): whether to keep calling that callback on each rendering call or not (act as a setInterval). Default to false

     returns:
     @queueItem: the queue item. Allows to keep a track of it and set its keep property to false when needed
*