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/gpu/doc/data_structures.rst

@@ -309,4 +309,3 @@ Class that enables getting ``cudaStream_t`` from :ocv:class:`gpu::Stream` and is
     {
         CV_EXPORTS static cudaStream_t getStream(const Stream& stream);
     };
-

modules/gpu/doc/introduction.rst

@@ -60,4 +60,3 @@ With this algorithm, a dual GPU gave a 180
 %
 performance increase comparing to the single Fermi GPU. For a source code example, see
 http://code.opencv.org/projects/opencv/repository/revisions/master/entry/samples/gpu/.
-