[paper 2] add plot diagnosis risk. refactor excess metric in study_visualizer_for_non_stationary_trends.py.

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

[Confidence Interval] use fix r.ci.fevd.mle_fixed for the Gumbel case in the Python code. fix the R code one more time for the gradient

[PAPER 1]  add dpi=1000 to every plot from the paper for image quality. add some fix ylim when plotting return level for the Maurienne

[PAPER 1] improve uncertainty plot. fix eurocode value for the histogram. modify number of bayesian iterations to 20000 for uncertainty plot