Conflicts:
	modules/calib3d/perf/perf_pnp.cpp
	modules/contrib/src/imagelogpolprojection.cpp
	modules/contrib/src/templatebuffer.hpp
	modules/core/perf/opencl/perf_gemm.cpp
	modules/cudafeatures2d/doc/feature_detection_and_description.rst
	modules/cudafeatures2d/perf/perf_features2d.cpp
	modules/cudafeatures2d/src/fast.cpp
	modules/cudafeatures2d/test/test_features2d.cpp
	modules/features2d/doc/feature_detection_and_description.rst
	modules/features2d/include/opencv2/features2d/features2d.hpp
	modules/features2d/perf/opencl/perf_brute_force_matcher.cpp
	modules/gpu/include/opencv2/gpu/gpu.hpp
	modules/gpu/perf/perf_imgproc.cpp
	modules/gpu/perf4au/main.cpp
	modules/imgproc/perf/opencl/perf_blend.cpp
	modules/imgproc/perf/opencl/perf_color.cpp
	modules/imgproc/perf/opencl/perf_moments.cpp
	modules/imgproc/perf/opencl/perf_pyramid.cpp
	modules/objdetect/perf/opencl/perf_hogdetect.cpp
	modules/ocl/perf/perf_arithm.cpp
	modules/ocl/perf/perf_bgfg.cpp
	modules/ocl/perf/perf_blend.cpp
	modules/ocl/perf/perf_brute_force_matcher.cpp
	modules/ocl/perf/perf_canny.cpp
	modules/ocl/perf/perf_filters.cpp
	modules/ocl/perf/perf_gftt.cpp
	modules/ocl/perf/perf_haar.cpp
	modules/ocl/perf/perf_imgproc.cpp
	modules/ocl/perf/perf_imgwarp.cpp
	modules/ocl/perf/perf_match_template.cpp
	modules/ocl/perf/perf_matrix_operation.cpp
	modules/ocl/perf/perf_ml.cpp
	modules/ocl/perf/perf_moments.cpp
	modules/ocl/perf/perf_opticalflow.cpp
	modules/ocl/perf/perf_precomp.hpp
	modules/ocl/src/cl_context.cpp
	modules/ocl/src/opencl/haarobjectdetect.cl
	modules/video/src/lkpyramid.cpp
	modules/video/src/precomp.hpp
	samples/gpu/morphology.cpp

Easier to understand

Move declaration of IVideoCapture class into precomp.hpp, make some methods of IVideoCapture pure virtual