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

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

Conflicts:
	doc/tutorials/definitions/noContent.rst
	doc/tutorials/gpu/gpu-basics-similarity/gpu-basics-similarity.rst
	doc/tutorials/introduction/android_binary_package/dev_with_OCV_on_Android.rst
	doc/tutorials/introduction/how_to_write_a_tutorial/how_to_write_a_tutorial.rst
	modules/core/include/opencv2/core/core.hpp
	modules/core/include/opencv2/core/internal.hpp
	modules/core/include/opencv2/core/version.hpp
	modules/gpu/CMakeLists.txt
	modules/highgui/perf/perf_output.cpp
	modules/highgui/test/test_video_io.cpp
	modules/ocl/include/opencv2/ocl/ocl.hpp
	modules/ocl/perf/main.cpp
	modules/ocl/src/hog.cpp
	modules/ocl/src/initialization.cpp
	modules/ocl/src/moments.cpp
	modules/ocl/src/opencl/moments.cl
	modules/ocl/test/main.cpp
	modules/ocl/test/test_moments.cpp
	modules/python/test/test.py
	modules/ts/include/opencv2/ts/ts_perf.hpp
	modules/ts/src/precomp.hpp
	modules/ts/src/ts_perf.cpp