Lifelines

New features
- new `print_summary` option `style` to print HTML, LaTeX or ASCII output
- performance improvements for `CoxPHFitter` - up to 30% performance improvements for some datasets.

Bug fixes
- fixed bug where computed statistics were not being shown in `print_summary` for HTML output.
- fixed bug where "None" was displayed in models' `__repr__`
- fixed bug in `StatisticalResult.print_summary`
- fixed bug when using `print_summary` with left censored models.
- lots of minor bug fixes.

New features
- new `print_summary` abstraction that allows HTML printing in Jupyter notebooks!
- silenced some warnings.

Bug fixes
- The "comparison" value of some parametric univariate models wasn't standard, so the null hypothesis p-value may have been wrong. This is now fixed.
- fixed a NaN error in confidence intervals for KaplanMeierFitter

API Changes

- To align values across models, the column names for the confidence intervals in parametric univariate models `summary` have changed.
- Fixed typo in `ParametricUnivariateFitter` name.
- `median_` has been removed in favour of `median_survival_time_`.
- `left_censorship` in `fit` has been removed in favour of `fit_left_censoring`.

The tests were re-factored to be shipped with the package. Let me know if this causes problems.


Bug fixes
- fixed error in plotting models with "lower" or "upper" was in the label name.
- fixed bug in plot_covariate_groups for AFT models when >1d arrays were used for values arg.

Bug fixes
- fixed `predict_` methods in AFT models when `timeline` was not specified.
- fixed error in `qq_plot`
- fixed error when submitting a model in `qth_survival_time`
- `CoxPHFitter` now displays correct columns values when changing alpha param.

New features
- Serializing lifelines is better supported. Packages like joblib and pickle are now supported. Thanks AbdealiJK!
- `conditional_after` now available in `CoxPHFitter.predict_median`
- Suppressed some unimportant warnings.

Bug fixes
- fixed initial_point being ignored in AFT models.

New features
- new `ApproximationWarning` to tell you if the package is making an potentially mislead approximation.

Bug fixes
- fixed a bug in parametric prediction for interval censored data.
- realigned values in `print_summary`.
- fixed bug in `survival_difference_at_fixed_point_in_time_test`

API Changes

- `utils.qth_survival_time` no longer takes a `cdf` argument - users should take the compliment (1-cdf).
- Some previous `StatisticalWarnings` have been replaced by `ApproximationWarning`