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/features2d/src/bagofwords.cpp

@@ -176,10 +176,10 @@ void BOWImgDescriptorExtractor::compute( const Mat& image, std::vector<KeyPoint>
 
     // Normalize image descriptor.
     imgDescriptor /= descriptors.rows;
-	
+
     // Add the descriptors of image keypoints
     if (_descriptors) {
-        *_descriptors = descriptors.clone(); 
+        *_descriptors = descriptors.clone();
     }
 }