* Extracted base64 persistence functionality

* Extracted YML persistence functionality

* Extracted JSON persistence functionality

* Extracted XML persistence functionality

* Extracted public C and C++ interfaces implementation in persistence

* Persistence: cleanup and fixes

* fixup! Persistence: cleanup and fixes

* Intel Inference Engine deep learning backend.

* OpenFace network using Inference Engine backend

* dnn: add colorization.cpp

* Update arguments of dnn/colorization.py

* Added tool to generate text graph for SSD models from TensorFlow

* Update tf_text_graph_ssd.py

Fix issue #10781.

CUDA code uses own implementation in cuda/limits.hpp

- removed tr1 usage (dropped in C++17)
- moved includes of vector/map/iostream/limits into ts.hpp
- require opencv_test + anonymous namespace (added compile check)
- fixed norm() usage (must be from cvtest::norm for checks) and other conflict functions
- added missing license headers

* old types removed

* QueryHist tests: new types

* ThreshHist tests: new types

* CalcHist tests: new types

* CalcBackProject tests: new types

* CalcBackProjectPatch tests: new types

* const ref added

* Fixing a bug in Canny implemetation when Sobel aperture size is 7.

* Fixing the bug in Canny accross variants and in test_canny.cpp

* Replacing a tab with white space

Add ocl version BackgroundSubtractorKNN (#10553)

* Add ocl version bgfg_knn

* Add ocl KNN perf test

* ocl KNN: Avoid unnecessary initializing when non-UMat parameters are used

* video: turn off OpenCL for color KNN on Intel devices

due performance degradation

* video: turn off KNN OpenCL on Apple devices with Intel iGPU

due process freeze during clBuildProgram() call