- some of `icvCvt_BGR*` functions have R with B channels
  swapped what leads to the wrong conversion
- renames misleading `rgb` variable name to `bgr`
- swap back the conversion coefficients, `cB` should be the first

Signed-off-by: Janusz Lisiecki <jlisiecki@nvidia.com>

When building OpenCV as a sub-project using cmake's add_subdirectory()
the OpenCV's build options would be overwritten to its default
state. With cmake 3.13+ the CMP0077 policy, option() honors previous
definitions via set().

* Changed plus operator to os.path.join()

* Remove '/' from PATH

* core: fix intrin_cpp, allow to build modules with SIMD emulator

* core(arithm): fix v_zero initialization

* core(simd): 'strict' types for binary/bitwise operations

* features2d: avoid aligned load issue in GCC 5.4 with emulated SIMD

* core(simd): alignment checks in SIMD emulator

Python code examples for file IO in xml and yml format

* Initial "Pythonization" of file_input_output.cpp

* Moved file_input_output.py to correct location

* Nearly done Pythonizing file_input_output.cpp

* Python equivalent of file_input_output.py created

* Started Pythonizing camera_calibration.cpp

* Completed Python tutorial/sample code for file_input_output

* Resolved whitespace issues

* Removed tabs in file_input_output.cpp

* Patched import order and wrapped code in main function

* Changed string to docstring format in help file

* Updated link to Python example code

* Added java code for meanshift and optical_flow

* added java code for module video

* added appropriate spaces in codes

* converted absolute path to command line arguments

* added spaces at appropriate places