Merge branch 'misc_tweaks' into 'master'

.gitlab-ci.yml

README.md

ci/install_basics.sh

ci/install_h5py.sh

ci/install_mpi4py.sh

ci/install_pyHealpix.sh

ci/install_pyfftw.sh

nifty/field_types/field_array.py

...rators/fft_operator/transformations/gllmtransformation.py

...rators/fft_operator/transformations/hplmtransformation.py

...rators/fft_operator/transformations/lmgltransformation.py

...rators/fft_operator/transformations/lmhptransformation.py

...y/operators/fft_operator/transformations/rg_transforms.py

...rs/invertible_operator_mixin/invertible_operator_mixin.py

...ators/propagator_operator/harmonic_propagator_operator.py

...operators/smoothing_operator/direct_smoothing_operator.py

nifty/operators/smoothing_operator/fft_smoothing_operator.py

nifty/spaces/power_space/power_space.py

nifty/spaces/space/space.py

nifty/sugar.py