switch to pyHealpix and adjust dependencies accordingly

.gitlab-ci.yml

Dockerfile

README.md

ci/install_h5py.sh

ci/install_libsharp.sh

ci/install_pyfftw.sh

ci/requirements.txt

ci/requirements_base.txt

nifty/config/nifty_config.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

nifty/spaces/gl_space/gl_space.py

nifty/spaces/hp_space/hp_space.py

nifty/spaces/lm_space/lm_space.py

test/common.py

test/test_spaces/test_gl_space.py

test/test_spaces/test_hp_space.py

test/test_spaces/test_interface.py