Merge remote-tracking branch 'origin/2.4' into merge-2.4

Conflicts:
	modules/contrib/src/retina.cpp
	modules/gpu/perf/perf_video.cpp
	modules/gpuoptflow/src/tvl1flow.cpp
	modules/ocl/include/opencv2/ocl/ocl.hpp
	modules/ocl/perf/perf_calib3d.cpp
	modules/ocl/perf/perf_color.cpp
	modules/ocl/perf/perf_match_template.cpp
	modules/ocl/src/precomp.hpp
	samples/gpu/stereo_multi.cpp

modules/bioinspired/src/retina.cpp

@@ -628,6 +628,7 @@ void RetinaImpl::_init(const cv::Size inputSz, const bool colorMode, int colorSa
            delete _retinaFilter;
     _retinaFilter = new RetinaFilter(inputSz.height, inputSz.width, colorMode, colorSamplingMethod, useRetinaLogSampling, reductionFactor, samplingStrenght);
 
+    _retinaParameters.OPLandIplParvo.colorMode = colorMode;
     // prepare the default parameter XML file with default setup
     setup(_retinaParameters);