Merge remote-tracking branch 'upstream/3.4' into merge-3.4

diff --cc cmake/OpenCVFindLibsGrfmt.cmake
Simple merge

diff --cc cmake/OpenCVUtils.cmake
Simple merge

diff --cc doc/tutorials/imgproc/pyramids/pyramids.markdown
Simple merge

diff --cc modules/calib3d/src/calibinit.cpp
Simple merge

diff --cc modules/calib3d/test/test_chesscorners.cpp
Simple merge

diff --cc modules/core/include/opencv2/core.hpp
Simple merge

diff --cc modules/core/include/opencv2/core/cvdef.h
Simple merge

diff --cc modules/core/include/opencv2/core/simd_intrinsics.hpp
Simple merge

diff --cc modules/core/src/matrix_operations.cpp
Simple merge

diff --cc modules/core/src/matrix_wrap.cpp
Simple merge

diff --cc modules/dnn/src/layers/proposal_layer.cpp
Simple merge

diff --cc modules/dnn/test/test_darknet_importer.cpp
Simple merge

diff --cc modules/highgui/CMakeLists.txt
Simple merge

diff --cc modules/imgcodecs/CMakeLists.txt
Simple merge

diff --cc modules/video/src/lkpyramid.cpp
Simple merge

diff --cc samples/cpp/tutorial_code/calib3d/camera_calibration/camera_calibration.cpp
Simple merge