[exceeding] fix code to create a qqplot. (sort only once the empirical quantiles have been computed). Create ALTITUDE_TO_GREY_MASSIF in utils to ensure that the exceedance plots are always done with the same massifs everywhere (and these massifs are only the one that are not grey for the non-stationary gev & gumbel)

[exceeding] update style of the qqplot. clean study_visualizer_for_non_stationary_trends.py, add a mode with only selected models that does not crash.

[contrasting] add quadratic model for gumbel/gev and location/scale. modify code for the name of the models

[paper 1] add error bars to uncertainty plot. add time series of maxima curve plot for 600m increasing case. add colorbar when necesasry for the trend plot.

[paper 1] refactor study visualizer using "model subset for uncertainty" name instead of unclear names.

[PAPER 1] refactor folder names in the paper snow load folder. add mani gelman convergence test. add the possibility to change the number of iterations for the bayesian fevd estimation