Btyd

- add mcmc.setBurnin method which cuts away (additional) initial burnin steps of MCMC chains
- `*.EstimateParameters` and `*.mcmc.DrawParameters` now also accept data.tables as input
- pcnbd.mcmc.plotRegularityRateHeterogeneity: add option to plot point estimates
- add mcmc.PActive and mcmc.plotPActiveDiagnostic

- deprecated `abe.mcmc.DrawFutureTransactions` and `pcnbd.mcmc.DrawFutureTransactions` in favor of newly add `mcmc.DrawFutureTransactions` method
- deprecated `abe.mcmc.PAlive` and `pcnbd.mcmc.PAlive` in favor of newly added `mcmc.PAlive` method
- `*.mcmc.DrawParameters` now all consistenly return sampled `z` values in their output


Changelog

- `ModBetaGeoModel` Bayesian implementation of Modified BG/NBD model added.
- Added `conditional_probability_of_being_alive_up_to_time` to `ParetoNBDFitter`.
- Removed CSV model persistence and added a validation check for loading models from JSON files.
- Removed `dill` dependency for persisting `fitters` models.
- Converted `_check_inputs` into a static method and added a validation check for 'frequency < T'.
- Converted `_dataframe_parser` from a static method and removed unnecessary `_check_inputs` call.
- Removed direct imports for `BaseModel` and `PredictMixin`.

- `GammaGammaModel` Bayesian implementation of Gamma-Gamma model added.
- Input validation added to `BaseModel` class.
- Fixed array broadcasting bug in `BetaGeoModel`.
- Revised frequency and monetary value descriptions in User Guide.
- Revised SQL code for monetary value calculations in documentation.
- Added required dependencies to `setup.cfg`.

- Bayesian predictions now supported, enabling entire probability distributions as well as point estimates for predictive outputs.
- Streamlined user API to minimize input arguments. All predictive methods are now also called from a single function.
- `model._idata` attribute now persisted as an `arviz.InferenceData` object, and can be saved externally in JSON or CSV format. However, only JSONs can be loaded as of this release.
- Documentation updated to latest versions of `sphinx` and `pydata-sphinx-theme`.
- Removed *High Level Overview* from documentation.
- Added deprecation warning for legacy Lifetimes `fitters` module.
- Removed extraneous `lifetimes` import causing build issues.
- Removed `psutils` library dependency.
- Added `numpy >=1.20.0` library dependency.
- `utils.posterior_predictive_deviation` metric removed pending further evaluation.
- CI/CD pre-commit scripts added.

- Forked `lifetimes` library v0.11.3 and rebranded as `btyd`.
- `BetaGeoCovarsFitter` BG/NBD model with time-invariant covariates added to `fitters` module.
- Alpha version of new modeling backend created in `models` module to support Bayesian modeling via `pymc`.
- `BetaGeoModel` Bayesian implementation of BG/NBD model added.
- Switched to Apache 2.0 license.
- New experimental `posterior_predictive_deviation` metric added.