[refactor] refactor code for article 1, to make it work. remove station data folder. deactivate normalize()

[refactor] refactor one fold fit, enable to get sorted estimators with other selection criterion without more computation

[refactor] add cached property on nllh, rename function from fit to margin function from fit. rename nb params to nb params from margin function

[refactor] rename function from fit to margin function from fit. remove sorted_estimators_with_stationary