speedup, bugfix and improvements

.gitlab-ci.yml

docs/notebooks/Optimization.ipynb

py_wake/deficit_models/noj.py

py_wake/flow_map.py

py_wake/site/xrsite.py

py_wake/tests/check_speed.py

py_wake/tests/test_notebooks.py

py_wake/tests/test_sites/test_xrsite.py

py_wake/tests/test_utils/test_eqdistance_interpolator.py

py_wake/turbulence_models/crespo.py

py_wake/turbulence_models/gcl.py

py_wake/utils/area_overlapping_factor.py

py_wake/utils/eq_distance_interpolator.py

py_wake/wind_farm_models/engineering_models.py