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

diff --cc 3rdparty/ffmpeg/ffmpeg.cmake
Simple merge

diff --cc cmake/OpenCVMinDepVersions.cmake
index f08fa57,a7e2477..d962780
--- 1/cmake/OpenCVMinDepVersions.cmake
--- 2/cmake/OpenCVMinDepVersions.cmake
+++ b/cmake/OpenCVMinDepVersions.cmake
@@@ -1,6 -1,6 +1,6 @@@
 -set(MIN_VER_CMAKE 2.8.12.2)
 +set(MIN_VER_CMAKE 3.5.1)
  set(MIN_VER_CUDA 6.5)
- set(MIN_VER_PYTHON2 2.6)
+ set(MIN_VER_PYTHON2 2.7)
  set(MIN_VER_PYTHON3 3.2)
  set(MIN_VER_ZLIB 1.2.3)
  set(MIN_VER_GTK 2.18.0)

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

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

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

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

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

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

diff --cc modules/dnn/src/onnx/onnx_importer.cpp
Simple merge

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

diff --cc modules/js/src/core_bindings.cpp
Simple merge

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