Subscribes an MessageHandler<T>(T) to be called back when a T object is published.
System.IDisposable Subscribe<T>(DefaultEcs.MessageHandler<T> action);
T
The type of the object to be called back with.
action
DefaultEcs.MessageHandler<T>
The delegate to be called back.
System.IDisposable
An System.IDisposable object used to unsubscribe.