dnn: small fix in pose estimation model

cuda4dnn(concat): write outputs from previous layers directly into concat's output

* eliminate concat by directly writing to its output buffer

* fix concat fusion not happening sometimes

* use a whitelist instead of a blacklist

Adding python codes to samples/python

* Python version of samples:
- laplace.py
- drawing.py

* Update drawing.py

* Update drawing.py

* Update drawing.py

* Update laplace.py

* Update laplace.py

* Update drawing.py

* Update drawing.py

* Update laplace.py

* samples

* drawing

* drawing

* drawing.py

* cmake: allow customization of CMAKE_CXX_STANDARD value

* cmake: extra skip flag OPENCV_SKIP_CMAKE_CXX_STANDARD

* cmake: dump CMAKE_CXX_STANDARD value

- compiler option is missing in dumped flags

use const instead of constexpr

* dnn(test): test DLDT IRv10 model, drop old models

* dnn(test): don't expect bitexact results in DLDT IR tests

* G-API/Samples: Added a simple "privacy masking camera" sample

The main idea is to host this code for an opencv.org blog post only

* G-API/Samples: Modified privacy masking camera code to look better for the post

* G-API/Samples: fix Windows (MSVC) support in Privacy Masking Camera

* G-API/Samples: Addressed the majority of review comments in PMC

* G-API/Samples: Use TickMeter to measure time + more info in cmd options

* G-API/Samples: fix yet another Windows warning in PMC

* G-API/Samples: Fix wording in PMC cmd arg parameters

* Fix wording, again

* G-API/Samples: Fix PMC cmd-line arguments, again

G-API: Using functors as kernel implementation

* Implement ability to create kernel impls from functors

* Clean up

* Replace make_ocv_functor to ocv_kernel

* Clean up

* Replace GCPUFunctor -> GOCVFunctor
* Move GOCVFunctor to cv::gapi::cpu namespace

* Implement override for rvalue and lvalue cases

* Fix comments to review

* Remove GAPI_EXPORT for template functions

* Fix indentation

Add CP-VTON sample

* Support resize from PyTorch

* Add CP-VTON sample

* Fix downsampling

* Fix test

* Add model links

* Add default args

* Speed up resize

* Fix TOM link

* Add default args

* Fix comments

* Set aspect ratio for input

* Update links

* Check files exist

fixed cv::moveWindow() on mac

* fixed cv::moveWindow() on mac (issue #16343). Thanks to cwreynolds and saskatchewancatch for the help!

* fixed warnings about _x0 and _y0

* fixed warnings about _x0 and _y0

* Fix NN resize with dimentions > 4

* add test check for nn resize with channels > 4

* Change types from float to double

* Del unnecessary test file. Move nn test to test_imgwarp. Add 5 channels test only.

* fixed typo

* add compatibility code to handle migration

* fixed Split layer in ONNXImporter

* added test for fix of split layer

* fixed tests for Split layer

* applied reviews

* updated tests

* fixed paths in tests

* improved version of HoughCircles (HOUGH_GRADIENT_ALT method)

* trying to fix build problems on Windows

* fixed typo

* * fixed warnings on Windows
* make use of param2. make it minCos2 (minimal value of squared cosine between the gradient at the pixel edge and the vector connecting it with circle center). with minCos2=0.85 we can detect some more eyes :)

* * added description of HOUGH_GRADIENT_ALT
* cleaned up the implementation; added comments, replaced built-in numeic constants with symbolic constants
* rewrote circle_popcount() to use built-in popcount() if possible
* modified some of HoughCircles tests to use method parameter instead of the built-in loop

* fixed warnings on Windows

trying to fix handling file storages with extremely long lines

* trying to fix handling of file storages with extremely long lines: https://github.com/opencv/opencv/issues/11061

* * fixed errorneous pointer access in JSON parser.
* it's now crash-test time! temporarily set the initial parser buffer size to just 40 bytes. let's run all the test and check if the buffer is always correctly resized and handled

* fixed pointer use in JSON parser; added the proper test to catch this case

* fixed the test to make it more challenging. generate test json with
*
**
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etc. shape