Added a check of the DetectionBasedTracker's inner state in the main thread function of this class. 
This change should fix a multithread bug in the class.

linetype -> lineType

FaceRecognizer class is now derived from Algorithm, therefore it's possible to set and retrieve the parameters using conventional Algorithm::set and Algorithm::get methods

fixed 2 build problems on MacOSX (highgui with ffmpeg, opencv_world); added macro CV_INIT_ALGORITHM for simpler algorithm registration (ticket #1876)

Added new performance tests for calcOpticalFlowPyrLK and buildOpticalFlowPyramid; extracted private header from lkpyramid.cpp