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/nonfree/test/test_detectors.cpp

@@ -312,6 +312,3 @@ void CV_DetectorsTest::run( int /*start_from*/ )
 
 
 TEST(Features2d_Detectors, regression) { CV_DetectorsTest test; test.safe_run(); }
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