Implemented WorldLightning and WorldThingDestroyed.

src/p_mobj.cpp

@@ -5108,6 +5108,12 @@ void AActor::CallDeactivate(AActor *activator)
 
 void AActor::OnDestroy ()
 {
+	// [ZZ] call destroy event hook.
+	//      note that this differs from ThingSpawned in that you can actually override OnDestroy to avoid calling the hook.
+	//      but you can't really do that without utterly breaking the game, so it's ok.
+	//      note: if OnDestroy is ever made optional, E_WorldThingDestroyed should still be called for ANY thing.
+	E_WorldThingDestroyed(this);
+
 	ClearRenderSectorList();
 	ClearRenderLineList();