addManager method
Add a manager into this world. It can be retrieved later. World will notify this manager of changes to entity.
Implementation
void addManager(Manager manager) {
if (_managers.containsKey(manager.runtimeType)) {
throw ArgumentError.value(
manager,
'manager',
'A manager of type "${manager.runtimeType}" has already been added '
'to the world.');
}
_managers[manager.runtimeType] = manager;
_managersBag.add(manager);
manager._world = this;
}