Added Python versions of the VTK Book Examples Ch04.

src/Cxx.md

src/Cxx/IO/3DSImporter.cxx

src/Cxx/Rendering/ColoredSphere.cxx

src/Cxx/Rendering/Mace.cxx

src/Cxx/Rendering/TransformSphere.cxx

src/Cxx/Rendering/TransformSphere.md

src/Cxx/Visualization/LoopShrink.cxx

src/Cxx/Visualization/QuadricVisualization.cxx

src/Python.md

src/Python/IO/3DSImporter.py

src/Python/Rendering/ColoredSphere.md

src/Python/Rendering/ColoredSphere.py

src/Python/Rendering/Mace.py

src/Python/Rendering/TransformSphere.md

src/Python/Rendering/TransformSphere.py

src/Python/Visualization/LoopShrink.py

src/Python/VisualizationAlgorithms/QuadricVisualization.md

src/Python/VisualizationAlgorithms/QuadricVisualization.py