CamDavidsonPilon/lifelines: v0.22.0

New features

• Ability to create custom parametric regression models by specifying the cumulative hazard. This enables new and extensions of AFT models.
• percentile(p) method added to univariate models that solves the equation p = S(t) for t
• for parametric univariate models, the conditional_time_to_event_ is now exact instead of an approximation.

• In Cox models, the attribute hazards_ has been renamed to params_. This aligns better with the other regression models, and is more clear (what is a hazard anyways?)
• In Cox models, a new hazard_ratios_ attribute is available which is the exponentiation of params_.
• In regression models, the column names in confidence_intervals_ has changed to include the alpha value.
• In regression models, some column names in .summary and .print_summary has changed to include the alpha value.
• In regression models, some column names in .summary and .print_summary includes confidence intervals for the exponential of the value.
• Significant changes to internal AFT code.
• A change to how fit_intercept works in AFT models. Previously one could set fit_intercept to False and not have to set ancillary_df - now one must specify a DataFrame.

• for parametric univariate models, the conditional_time_to_event_ is now exact instead of an approximation.