Method configure

examples/example.cc:280–282

class ExplosionSystem : public ex::System<ExplosionSystem>, public ex::Receiver<ExplosionSystem> {
public:
  void configure(ex::EventManager &events) override {
    events.subscribe<CollisionEvent>(*this);
  }

  void update(ex::EntityManager &es, ex::EventManager &events, ex::TimeDelta dt) override {
    for (ex::Entity entity : collided) {