[EUROCODE GRAPH] update burn in percentage to 0.5 (update test). delete test region eurocode. update eurocode graph.

[EUROCODE DATA] improve display for the eurocode return level graphs. rename linear margin temporal models.

[EUROCODE][DRAWING PER REGION] modify test region eurocode. add test_ gev temporal bayesian. add stationary version for the Bayesian. refactor utils at the root, to root_uils to avoid weird import issues.