[contrasting] add quadratic model for gumbel/gev and location/scale. modify code for the name of the models

[contrasting] add assertion that the max_abs_change is different from np.inf otherwise it makes the computer freeze
IMPORTANT MODIFICATION, THAT MIGHT CHANGE PAPER 1: change unconstrained_estimator_gev_params to unconstrained_estimator_gev_params_last_year

[exceeding] add full diagnositic plot (qqplot & intensity plots) for gumbel stationary & add gumbel gof tests from r package

[exceeding] add full diagnositic plot (qqplot & intensity plots) for gumbel stationary & add gumbel gof tests from r package