[projection snowfall] add functions_utils.py. modify one_fold_fit.py so that it may support one altitude fit.

[projection snowfall] refactor nb_params. so that is it associated to the margin_function rather than to the margin_model.

[projection snowfall] adapt the one_fold_fit.py code to handle fit with a single altitude. Modify altitude_class by altitude_group, adapt tests. Modify the DefaultAltitudeGroup. adapt main_projections_ensemble.py

[projection snowfall] add spline simulation. implement splines for k=1. pass test_gev_temporal_spline.py

[projection snowfall] fix one issue for evgam coefficients. refactor param_name_to_dim -> param_name_to_dims in the result objects.

[projection snowfall] add spline_margin_function.py and test with it. test_gev_temporal_spline.py is not yet validated for the nllh.

[projection snowfall] add evgam call for abstract_temporal_linear_margin_model.py. account for log_scale in the margin_function. rename get_coord_df to get_r_dataframe_from_python_dataframe. create evgam_fixed.R for debugging

[projection snowfall] remove test with respect to fevd bayesian, due to differences with the test. i do not use it, so it does not matter. But maybe with the change of R version, the code changed. still try to install evgam

[projection snowfall] refactor first_year and last_year in OneFoldFit. and apply the code to check the difference in spatial patterns between safran 2020 reanalysis and ADAMont v2

[projection snowfall] add main_sensitivity_one_altitude_range.py. add detail plot for each massif for the return level

[projection swe] modify interval (and data constraint) for temperature sensitivity. add invidual plots in sensitivity. add changes plot in sensitivity.

[projection swe] add crpss and train train test. improve the plot. fix bug for selection of plausible models.

[projection swe] add model_as_truth.py. add default weight solver and a file for the method with bootstrap

[projection snowfall] add massif_names for cache computation in abstract_study.py. implement bootstrap indicator. add bootstrap return level that are physically plausible

[projection snowfall] add preliminary analysis for the work on model with effect related to the GCM or RCM type.

[projection snowfall] improve one_fold_fit_merge.py. improve interval for the sensitivity plot. Add is_temperature_interval and is_shift_interval to define the intervals.