[quantile regression project]  fix bugs in daily_observations.py for the creation of the coordinates for the daily fit. some fix to prepare for some potential non stationary exponential model one day

[contrasting project] add global mean temperature data, and add test for adding these covariate to the coordinates.

[contrasting project] fix memory issue that was happening while loading many precipitation studies. issue #300

[quantile regression project] refactor imports for quantile estimators. two fix: nb_obs=1 in GevSimulation.py and df_merged correspond to df_coordinates from now on (such as it takes into account the transformation if there is one)

[EUROCODE][DRAWING PER REGION] modify test region eurocode. add test_ gev temporal bayesian. add stationary version for the Bayesian. refactor utils at the root, to root_uils to avoid weird import issues.

[COORDINATE] refactor starting year & df_temporal_coordinates. to normalize the same way any temporal covariate. So that each fit has the same type of normalized data as input. add multiple transformation.

[SCM][HYPERCUBE] normalize gev trend_strength with distance between years. update test to check this distance.

[COORDINATES] add one test to test_transformation. add some copying during coordinate transformation.

[DATASET] add creation of spatio temporal dataset from simulation. add test for non stationarity of max stable

[TEST][DATASET] major fix for abstract_dataset for the function transform_maxima in the spatio temporal case

[SIMULATION] add constant estimators. handle graph plot of constant margin estimator (when the sampling margin was also constant)