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

diff --cc doc/Doxyfile.in
Simple merge

diff --cc doc/tutorials/calib3d/real_time_pose/real_time_pose.markdown
Simple merge

diff --cc modules/calib3d/include/opencv2/calib3d.hpp
Simple merge

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

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

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

diff --cc modules/dnn/src/ie_ngraph.cpp
index 49717f8,3b87243..7484032
--- 1/modules/dnn/src/ie_ngraph.cpp
--- 2/modules/dnn/src/ie_ngraph.cpp
+++ b/modules/dnn/src/ie_ngraph.cpp
@@@ -684,9 -684,26 +687,26 @@@ void InfEngineNgraphNet::initPlugin(Inf
                      InferenceEngine::PluginConfigParams::KEY_CPU_THREADS_NUM, format("%d", getNumThreads()),
                  }}, device_name);
  #endif
+ #if INF_ENGINE_VER_MAJOR_GE(INF_ENGINE_RELEASE_2021_2)
+             if (device_name.find("GPU") == 0)
+             {
+ #if OPENCV_HAVE_FILESYSTEM_SUPPORT
+                 std::string cache_path = utils::fs::getCacheDirectory((std::string("dnn_ie_cache_") + device_name).c_str(), "OPENCV_DNN_IE_GPU_CACHE_DIR");
+ #else
+                 std::string cache_path = utils::getConfigurationParameterString("OPENCV_DNN_IE_GPU_CACHE_DIR", "");
+ #endif
+                 if (!cache_path.empty() && cache_path != "disabled")
+                 {
+                     CV_LOG_INFO(NULL, "OpenCV/nGraph: using GPU kernels cache: " << cache_path);
+                     ie.SetConfig({{
+                         InferenceEngine::PluginConfigParams::KEY_CACHE_DIR, cache_path,
+                     }}, device_name);
+                 }
+             }
+ #endif
          }
          std::map<std::string, std::string> config;
 -        if (device_name == "MYRIAD") {
 +        if (device_name == "MYRIAD" || device_name == "HDDL") {
  #if INF_ENGINE_VER_MAJOR_GT(INF_ENGINE_RELEASE_2020_4)
              config.emplace("MYRIAD_DETECT_NETWORK_BATCH", CONFIG_VALUE(NO));
  #else

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

diff --cc modules/imgproc/src/contours.cpp
Simple merge

diff --cc modules/imgproc/src/templmatch.cpp
Simple merge

diff --cc modules/imgproc/test/test_contours.cpp
Simple merge

diff --cc modules/imgproc/test/test_templmatch.cpp
Simple merge

diff --cc modules/stitching/src/matchers.cpp
Simple merge