arviz-devs/arviz: Beta release

Highlights Added to_dataframe method, __getitem__ magic and copy method to InferenceData Add ref_line, bar, vlines and marker_vlines kwargs to plot_rank Add observed argument to (un)plot observed data in plot_ppc Add support for named dims and coordinates with multivariate observations Add support for discrete variables in rank plots and loo_pit Make stacking the default method to compute weights in compare (1438) [experimental] Modified SamplingWrapper base API Maintenance and fixes Updated CmdStanPy interface Have from_pystan store attrs as strings to allow netCDF storage Use circular KDE function and fix tick labels in circular plot_trace Fix computation of weights in compare Add grid argument to manually specify the number of rows and columns Switch to compact=True by default in our plots Make from_pymc3 compatible with theano-pymc 1.1.0 Deprecations * plot_khat deprecate annotate argument in favor of threshold. See detailed change lo