- don't require "OPENCV_PYTHON{2,3}_INSTALL_PATH" if OPENCV_SKIP_PYTHON_LOADER=ON
- avoid unnecessary relative paths in generated config-X.Y.py

Configures and loads OpenCV bindings extension including 3rdparty dependencies

Based on running Python specify:
- configure PYTHON_PATH (via "sys.path")
- configure LD_LIBRARY_PATH / PATH

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- The `sysconfig` key `SO` is deprecated, it has been replaced by `EXT_SUFFIX`

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

- 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

numpy 1.13.0+

Also fixes issue with empty PYTHON_PACKAGES_PATH (cross-compilation mode)

Adding of destructor and placement new constructors for classes wrapped with CV_EXPORTS_W_SIMPLE macro

Explicitly linking to a Python framework on OS X prevents modules from
being built against one Python (i.e. system python) and imported from
another (i.e. Homebrew python); the interpreter segfaults if there's a
linkage to a foreign Python. Building the module with `-undefined
dynamic_lookup` instead of an explicit link allows the symbols to be
resolved at load time from a compatible python.

- added java wrapper
- disabled python wrapper

don't discard pure virtual methods in hdr_parser.py (was broken anyway)

fixed find_obj.py

maintain set of visited namespaces in CppHeaderParser
WARNING: REMOVED const name conversion (SomeConstName -> SOME_CONST_NAME), discussion needed