Merge branch 'develop' into 'release_v1.2.0'

.gitignore

.gitlab/issue_templates/bug.md

.gitlab/issue_templates/release.md

conftest.py

docs/_source/_plots/data_availability_histogram_hist.png

docs/_source/_plots/data_availability_histogram_hist_cum.png

docs/_source/_plots/skill_score_bootstrap_separated.png

mlair/__init__.py

mlair/configuration/defaults.py

mlair/configuration/path_config.py

mlair/data_handler/advanced_data_handler.py

mlair/data_handler/data_handler_mixed_sampling.py

mlair/data_handler/data_handler_neighbors.py

mlair/data_handler/data_handler_single_station.py

mlair/data_handler/default_data_handler.py

mlair/data_handler/iterator.py

mlair/helpers/__init__.py

mlair/helpers/datastore.py

mlair/helpers/helpers.py

mlair/helpers/join.py