[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

[Thesis committee drawing] improve GEV non stationary plots.  rename ci_delta to ci_mle. catch some ci runtime exceptions. remove hatch/stripes drawing temporarily. fix unit for snow load. add new crocus classes & variable classes for snow load. modify conversion factor only for the new plots.

[CONFIDENCE INTERVAL] in the non stationary case, only the normal method is defined. in the stationary, i managed to add test the "boot" method. But for the "proflik" method there was a crash in R related to the spline, that i did not resolve

[CONFIDENCE INTERVAL] add confidence interval test for the normal (i.e. delta) confidence interval method

[CONFIDENCE INTERVAL] check that ci code return the same interval and mean posterior for the return level as my code with coordinates from 0 to 49. and also with transformed coordinates

[EXTREME ESTIMATOR] add test confidence interval. Add confidence interval with the ci method in the Bayesian case. add test for the stationary case. put the division by 100 (to get snow load) in eurocode vizualizer