Helper functions to register sample implementations of the ForEachEntity and ForEachEntityWithout meta Components.
template<typename Comp>
void registerComponentEntityIterator(EntityManager & em);Implements the ForEachEntity and ForEachEntityWithout meta Components for Comp.
template<typename ... Comps>
void registerComponentEntityIterators(EntityManager & em);Calls registerComponentEntityIterator<T> for each T in Comps.