Added some nice beat detection
Raised maximal delay on trackbar to 3000 from 1000
For more comfortable analysis of videos.
SoundPlayer::play: Removed debug output
SoundPlayer: Now has configurable frequency
BallBeatEstimator: Added SoundPlayer
SoundPlayer: Exposed note length
SoundPlayer: Optimized length handling; removed `update` method
`update` is no longer necessary. Playback stops by itself after `length` seconds.
BeatEstimator.cpp: Removed obsolete commented out code
Differentiated beat estimators by sound (frequency)
BallBeatEstimator: Raised minimal frame gap between beats to 12
Works well for video recording from Bikofe.