message: Remove BasicCheck call from populationAvailable
  Now that it's private, with only two calls, with fixed parameters, it's
  impossible to call it with a bad parameter.
diff: @@ -39,10 +39,7 @@ int PopulationPool::availableScientists()
  */
  int PopulationPool::populationAvailable(PopulationTable::Role role)
  {
  - BasicCheck(role);
  -
  int employed = role == PopulationTable::Role::Scientist ? scientistsEmployed() : workersEmployed();
  -
  return mPopulation->size(role) - employed;
  }
  