- https://python.readthedocs.io/en/stable/whatsnew/3.4.html
- The `sysconfig` key `SO` is deprecated, it has been replaced by `EXT_SUFFIX`

* Remove isIntel check from deep learning layers

* Remove fp16->fp32 fallbacks where it's not necessary

* Fix Kernel::run to prevent localsize > globalsize

into cv::videoio_registry namespace

The result of PyUnicode_AsUTF8() is now of type const char * rather of 
char *.

- requires OpenCV source directory
- requires OpenCV binary directory with built modules and 'python_bindings_generator' target

Tested with:
- pylint 1.9.1

* Add Python support for error message handlers.

* Move the static variable to the only function that uses it.

* Remove the optional param (user data), since this can already be handled by closures.

* Correct the help string.

* python: added redirectError test

- Recommended compiler checks:
  - GCC: CV_GCC
  - Clang: CV_CLANG
- fixed problem with CMAKE_CXX_COMPILER_ID=Clang/AppleClang mess on MacOSX
  Details: cmake --help-policy CMP0025
- do not declare Clang as GCC compiler

My build fails with the error:
"C:/PROGRA~1/MINGW-~1/X86_64~1.0-P/mingw64/lib/gcc/x86_64-w64-mingw32/7.2.0/include/c++/cmath:1136:11: error: '::hypot' has not been declared".
I have tried to fix it by adding "#include <cmath>" before the line "#include <Python.h>" but then the build has failed with the error:
"C:/PROGRA~1/MINGW-~1/X86_64~1.0-P/mingw64/lib/gcc/x86_64-w64-mingw32/7.2.0/include/c++/math.h:91:12:: error: 'std::_hypot' has not been declared".
Adding "#include <math.h>" allowed me to build opencv.

Found via `codespell`

fix missing "opencv2/core/opencl" headers from core module (updated install list)

* persistence: replace arbitrary limit of cn to 4 by CV_CN_MAX

* python: added persistence test, remove temp files

* fixup! python: added persistence test, remove temp files

* fixup! python: added persistence test, remove temp files

Implementation of bit-exact resize. Internal calls to linear resize updated to use bit-exact version. (#9468)