Merge commit '43aec5ad' into merge-2.4

Conflicts:
	cmake/OpenCVConfig.cmake
	cmake/OpenCVLegacyOptions.cmake
	modules/contrib/src/retina.cpp
	modules/gpu/doc/camera_calibration_and_3d_reconstruction.rst
	modules/gpu/doc/video.rst
	modules/gpu/src/speckle_filtering.cpp
	modules/python/src2/cv2.cv.hpp
	modules/python/test/test2.py
	samples/python/watershed.py

modules/contrib/src/featuretracker.cpp

@@ -221,4 +221,3 @@ Point2f CvFeatureTracker::getTrackingCenter()
     center.y = (float)(prev_center.y + prev_trackwindow.height/2.0);
     return center;
 }
-