Upgrade LinearCellDemo and add a PythonicAPI version

src/Cxx.md

src/Cxx/GeometricObjects/LinearCellDemo.cxx

src/Cxx/GeometricObjects/LinearCellDemo.md

src/Python.md

src/Python/GeometricObjects/LinearCellDemo.md

src/Python/GeometricObjects/LinearCellDemo.py

src/PythonicAPI.md

src/PythonicAPI/GeometricObjects/LinearCellDemo.md

src/PythonicAPI/GeometricObjects/LinearCellDemo.py

...ting/Baseline/Cxx/GeometricObjects/TestLinearCellDemo.png

...g/Baseline/Python/GeometricObjects/TestLinearCellDemo.png

...eline/PythonicAPI/GeometricObjects/TestLinearCellDemo.png