[paper 2] rename safran precipitation total to safran precipitation. add snowfall, precipitation, and rainfall study classes for 1, 3, 5 and 7 days

[EUROCODE DATA] improve display for the eurocode return level graphs. rename linear margin temporal models.

[EXTREME ESTIMATOR] refactor margin_fits folder. extreme estimator folder. and extreme_models folder

[EXTREME ESTIMATOR][MARGIN MODEL] refactor linear margin model folder organization. refactor names in univariate trend analysis

[EXTREME ESTIMATOR][MAX STABLE] add test that check the possibility to fit max stable with 3D coordinates. This is working with all the max stable structure except Smith structure (see max_stable_fit.R for an example of the returned error)

[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.

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

[SCM] add permutation which correspond to the sum of rainfall & snowfall. add test based on Durand paper.

[SAFRAN] move safran directory inside experiment directory, add safran visualizer. add smooth marginal estimation & full estimation

[DATA] add safran extended (which include as massifs: the original massif + the 4 alps regions + the whole alps)

[MAX STABLE MODEL] add fitmaxstab for 1D coordinates (by building 2D coordinates from the 1D coordinates)