Add scheduling timing to EngineWorkerScheduler.
Add Uptime, a nanosecond-precision class for measuring time since Mixxx started up.
Build uptime.cpp.
Oops, use qint64 instead of int.
Add proto for describing audio features.
Add FeatureCollector, a new thread for processing features collected by the engine thread. Typical latencies for message processing are in the tens of microseconds at the expense of locking during the realtime callback. Should replace the message passing with a lock-free FIFO in the future.
Rename some Aubio constants.
Derive EngineBufferFeatureExtractor from AubioFeatureExtractor because we want to get features like FFT and onsets from Aubio even if we are getting beats from Mixxx.
Create a FeatureCollector in EngineMaster.
Write extracted features to the FeatureCollector instead of printing them.