v0.0.4.0

• Add new extensible S4 class based interface.
  • Step-by-step functions to construct sequence of target trial analysis. See the "New Interface"" vignette.
  • Possibility to add alternative data storage and model fitting functionality. See the "Extending TrialEmulation"
    vignette.
  • Use duckdb to store expanded data for efficient reading and sampling of large data.
  • Use parsnip models for weight model fitting (experimental, not recommended).
  • This interface is still "experimental" and may change in future
  • Thanks @darkgoldenrod-cherry

Full Changelog: v0.0.4...v0.0.4.0