G-API external backend development (#13943)

* Moved HostCtor and ConstVal from gapi_priv.hpp to objref.hpp

* Added gmodel_priv.hpp, added export of symbols from gmodel.hpp

* Added export of binInArg and bindOutArg

* Renamed gapi_priv.*pp -> gorigin.*pp

* Added a fixme on collecting exports inside one class

fix just a typo of the word 'word' (#14297)

* Add networks visualization

* Disable CXX11

* Fixed multy inputs support

* Added output shapes

* Added color for DLIE/CPU

* Fixed graph colors

* Add flushing to printing number of processed positive/negative samples so that user is informed of updates quickly.

* use flush C api instead of C++ api

* AVFoundation: Use runtime check for camera authorization

cmake: fix WITH_OPENCL_D3D11_NV check

* macosx: fix C++11 build

backporting commit c3cf35ab

* macosx: eliminate build warning

Do not use compound literals (fix MSVC C4576) (#14276)

* do not use compound literals (compat cpp98)

* only fix msvc path

* remove unnecessary cplusplus check

- added functionality to collect memory usage of OpenCL sybsystem
- memory usage of fastMalloc() (disabled by default):
  * It is not accurate sometimes - external memory profiler is required.
- specify common `CV_TEST_TAG_` macros
- added applyTestTag() function
- write memory usage / enabled tags into Google Tests output file (.xml)

OpenCV 4.1.0

OpenCV 3.4.6

- estimateAffine2D/estimateAffinePartial2D() calls

* Added authorization request to AVFoundation camera backend (OSX 10.14+)

oss-fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=13280
oss-fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=13283

* Fix decode and detectAndDecode Java wrappers for QRCodeDetector

* revert changes in objdetect

* java: fix wrapping of std::string type