added std::function callback benchmark, actually run the groups benchmark
added std::function callback benchmark, actually run the groups benchmark

2666hz/Cinder,sosolimited/Cinder,morbozoo/sonyHeadphones,sosolimited/Cinder,2666hz/Cinder,sosolimited/Cinder,2666hz/Cinder,morbozoo/sonyHeadphones,2666hz/Cinder,sosolimited/Cinder,morbozoo/sonyHeadphones,morbozoo/sonyHeadphones