Adding SpatioTemporalHarmonicsSource.py and documentation plus tweaks

src/Cxx.md

src/Cxx/Filtering/SpatioTemporalHarmonicsSource.cxx

src/Cxx/Filtering/SpatioTemporalHarmonicsSource.md

src/Cxx/GeometricObjects/GoldenBallSource.md

src/PythonicAPI.md

src/PythonicAPI/Filtering/SpatioTemporalHarmonicsSource.md

src/PythonicAPI/Filtering/SpatioTemporalHarmonicsSource.py

src/PythonicAPI/GeometricObjects/GoldenBallSource.md

...eline/Cxx/Filtering/TestSpatioTemporalHarmonicsSource.png

...thonicAPI/Filtering/TestSpatioTemporalHarmonicsSource.png