Merge branch '2.4'

diff --cc doc/tutorials/introduction/linux_gcc_cmake/linux_gcc_cmake.rst
Simple merge

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

diff --cc modules/core/doc/drawing_functions.rst
Simple merge

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

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

diff --cc modules/features2d/include/opencv2/features2d/features2d.hpp
Simple merge

diff --cc modules/features2d/src/features2d_init.cpp
Simple merge

diff --cc modules/highgui/doc/reading_and_writing_images_and_video.rst
Simple merge

diff --cc modules/imgproc/perf/perf_cvt_color.cpp
Simple merge

diff --cc modules/imgproc/perf/perf_resize.cpp
Simple merge

diff --cc modules/ts/src/ts_perf.cpp
Simple merge

diff --cc modules/video/doc/motion_analysis_and_object_tracking.rst
Simple merge