message: Use refernce syntax in fillPopulationRequirements
diff: /**
  * Fills population requirements fields in a Structure.
  */
  -static void fillPopulationRequirements(PopulationPool& _p, const PopulationRequirements* _populationRequired, PopulationRequirements* _populationAvailable)
  +static void fillPopulationRequirements(PopulationPool& _p, const PopulationRequirements& _populationRequired, PopulationRequirements& _populationAvailable)
  {
  // Verbose but a lot easier to read than the ternary operators I was using before.
  // WORKERS
  - if (_p.enoughPopulationAvailable(Population::PersonRole::ROLE_WORKER, (*_populationRequired)[0]))
  + if (_p.enoughPopulationAvailable(Population::PersonRole::ROLE_WORKER, _populationRequired[0]))
  {
  - (*_populationAvailable)[0] = (*_populationRequired)[0];
  + _populationAvailable[0] = _populationRequired[0];
  }
  else
  {
  - (*_populationAvailable)[0] = _p.populationAvailable(Population::PersonRole::ROLE_WORKER);
  + _populationAvailable[0] = _p.populationAvailable(Population::PersonRole::ROLE_WORKER);
  }
  // SCIENTISTS
  - if (_p.enoughPopulationAvailable(Population::PersonRole::ROLE_SCIENTIST, (*_populationRequired)[1]))
  + if (_p.enoughPopulationAvailable(Population::PersonRole::ROLE_SCIENTIST, _populationRequired[1]))
  {
  - (*_populationAvailable)[1] = (*_populationRequired)[1];
  + _populationAvailable[1] = _populationRequired[1];
  }
  else
  {
  - (*_populationAvailable)[1] = _p.populationAvailable(Population::PersonRole::ROLE_SCIENTIST);
  + _populationAvailable[1] = _p.populationAvailable(Population::PersonRole::ROLE_SCIENTIST);
  }
  }
  @@ -162,7 +162,7 @@ void StructureManager::updateStructures(StorableResources& resources, Population
  const auto& _populationRequired = structure->populationRequirements();
  auto& _populationAvailable = structure->populationAvailable();
  - fillPopulationRequirements(population, &_populationRequired, &_populationAvailable);
  + fillPopulationRequirements(population, _populationRequired, _populationAvailable);
  if (!population.enoughPopulationAvailable(Population::PersonRole::ROLE_WORKER, _populationRequired[0]) ||
  !population.enoughPopulationAvailable(Population::PersonRole::ROLE_SCIENTIST, _populationRequired[1]))
  