Merge branch 'do_cleanup' into 'NIFTy_6'

.gitlab-ci.yml

ChangeLog

demos/Wiener_Filter.ipynb

demos/bench_gridder.py

demos/bernoulli_demo.py

demos/find_amplitude_parameters.py

demos/getting_started_1.py

demos/getting_started_2.py

demos/getting_started_mf.py

demos/misc/convolution.py

demos/multi_amplitudes_consistency.py

demos/polynomial_fit.py

nifty6/__init__.py

nifty6/data_objects/__init__.py

nifty6/data_objects/distributed_do.py

nifty6/data_objects/numpy_do.py

nifty6/dobj.py

nifty6/domain_tuple.py

nifty6/domains/domain.py

nifty6/domains/lm_space.py