Using std::to_string instead of boost::lexical_cast to be compatible with icpc < 4.0.3 (see https://software.intel.com/en-us/forums/topic/474961)
PacketHandler now aggregates frames and the HandleFrameTask now processes several frames -> reduction of enqueued tbb tasks
PacketHandler now runs as separate thread again, not as a tbb::task
Merge branch 'feature/aggregatedFrameProcessing' of ssh://localhost:2000/NA62/na62-farm into feature/aggregatedFrameProcessing