* Figure out a way to include test cases in final planet package.

* Figure out a way to include test cases in final planet package.
  The problem is the require/expose; it causes problems with the planet
  loader, even if you require the -tests.ss file directly rather than via
  planet.

* Once I understand contract pragmatics, revisit env/c and fast-env/c.

* Perhaps a per-table default for item-not-found action?  Would be
  constructor argument

* Think about re-implementing in Carl's backend once he gets that in
  Planet.