Destroy event subsystem after scene.

src/context.cpp

@@ -24,12 +24,12 @@ Context::~Context() {
 	delete history;
 	history = NULL;
 
-	delete event;
-	event = NULL;
-
 	delete scene;
 	scene = NULL;
 
+	delete event;
+	event = NULL;
+
 	delete engine;
 	engine = NULL;
 }