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

[EXTREME ESTIMATOR] add margin_fits folder. add gpd params & gpdmle_fit. refactor code to handle gev and gpd together

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

[SIMULATION] add constant estimators. handle graph plot of constant margin estimator (when the sampling margin was also constant)