Merge branch 'master' into 'n-fixing'

.gitignore

.gitlab-ci.yml

ToDo.md

ci/requirements_py39.yml

ci/requirements_py39_cartopy19.yml

config_ckdtree/config_ckdtree_r2b4_atm_r0012_dwd.py

config_ckdtree/config_ckdtree_r2b4_atm_r0013_dwd.py

config_ckdtree/config_ckdtree_r2b4_oce_dwd.py

doc/attic/mistral.rst

doc/conf.py

doc/example_notebooks.rst

doc/index.rst

doc/installation.rst

doc/notebooks_nblink/examp_atm_2d_scalars.nblink

doc/notebooks_nblink/examp_atm_converting_omega_to_w.nblink

doc/notebooks_nblink/examp_atm_equation_of_state.nblink

doc/notebooks_nblink/examp_atm_geopotential_height.nblink

...ebooks_nblink/examp_atm_plot_zonally_averaged_data.nblink

doc/notebooks_nblink/examp_atm_plotting_era_data.nblink

doc/notebooks_nblink/examp_atm_wind_stress.nblink