=== Summary of Proposal ===

  - Add records for Ingredients and Drug forms containing standard units for each ingredient.
  - Define convention for quantity: Either as number of product unites, or as amount of ingredient. See below.
  - Remove effective_drug_dose.
  - Introduce verbatim_end_date. drug_exposure_end_date would no longer be nullable, and contain the verbatim, start_date+days_supply or a value that was determined through some ETL heuristic