Modernising the code, improving images

src/Cxx/PolyData/CMakeLists.txt

src/Cxx/PolyData/PolyDataCellNormals.cxx

src/Cxx/PolyData/PolyDataCellNormals.md

...Cxx/PolyData/PolyDataConnectivityFilter_LargestRegion.cxx

src/Cxx/PolyData/PolyDataConnectivityFilter_LargestRegion.md

...x/PolyData/PolyDataConnectivityFilter_SpecifiedRegion.cxx

...xx/PolyData/PolyDataConnectivityFilter_SpecifiedRegion.md

src/Cxx/PolyData/PolyDataContourToImageData.cxx

src/Cxx/PolyData/PolyDataExtractNormals.cxx

src/Cxx/PolyData/PolyDataExtractNormals.md

src/Cxx/PolyData/PolyDataGetPoint.cxx

src/Cxx/PolyData/PolyDataGetPoint.md

src/Cxx/PolyData/PolyDataIsoLines.cxx

src/Cxx/PolyData/PolyDataPointNormals.cxx

src/Cxx/PolyData/PolyDataPointNormals.md

src/Cxx/PolyData/PolyDataPointSampler.cxx

src/Cxx/PolyData/PolyDataPointSampler.md

src/Cxx/PolyData/PolyDataToImageData.cxx

src/Cxx/PolyData/PolyDataToUnstructuredGrid.cxx

src/Cxx/PolyData/PolygonalSurfaceContourLineInterpolator.cxx