STYLE : Improve pylint rated (part 2)

python_src/diapotb/lib/DInSAR.py

python_src/diapotb/lib/Ground.py

python_src/diapotb/lib/PostProcessing.py

python_src/diapotb/lib/PreProcessing.py

python_src/diapotb/lib/core/ApplicationWrapper.py

python_src/diapotb/lib/core/DiapOTBProcessing.py

python_src/diapotb/lib/internal_processing/filtering.py

python_src/diapotb/lib/internal_processing/resampling.py