Non-trivial updates:
- some vertical CRS are now encoded as DerivedVerticalCRS. e.g EPSG:8228
  "NAVD88 height (ft)", with base EPSG:5703 "NAVD88 height". As we don't
  have support in our PROJ db model for DerivedVerticalCRS, modify the
  import script to 'resolve' the derivation up to the original datum.
- Method EPSG:1069 'Change of Vertical Unit' is no longer used. It is
  replaced by a generic-purpose EPSG:1104 method that doesn't take any
  conversion factor. And generic conversions EPSG:7812 and EPSG:7813 are
  now used in concatenated operations, which require code changes as
  well.