Add trait interfaces for added/removed from world.

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -64,6 +64,8 @@ namespace OpenRA.Traits
 	public interface IValidateOrder { bool OrderValidation(OrderManager orderManager, World world, int clientId, Order order); }
 	public interface IOrderVoice { string VoicePhraseForOrder(Actor self, Order order); }
 	public interface INotify { void Play(Player p, string notification); }
+	public interface INotifyAddedToWorld { void AddedToWorld(Actor self); }
+	public interface INotifyRemovedFromWorld { void RemovedFromWorld(Actor self); }
 	public interface INotifySold { void Selling(Actor self); void Sold(Actor self); }
 	public interface INotifyDamage { void Damaged(Actor self, AttackInfo e); }
 	public interface INotifyDamageStateChanged { void DamageStateChanged(Actor self, AttackInfo e); }

OpenRA.Game/World.cs

@@ -159,6 +159,9 @@ namespace OpenRA
 			a.IsInWorld = true;
 			actors.Add(a);
 			ActorAdded(a);
+
+			foreach (var t in a.TraitsImplementing<INotifyAddedToWorld>())
+				t.AddedToWorld(a);
 		}
 
 		public void Remove(Actor a)
@@ -167,6 +170,8 @@ namespace OpenRA
 			actors.Remove(a);
 			ActorRemoved(a);
 
+			foreach (var t in a.TraitsImplementing<INotifyRemovedFromWorld>())
+				t.RemovedFromWorld(a);
 		}
 
 		public void Add(IEffect b) { effects.Add(b); }