Fix issue where buttons will cause heap corruption if they are removed from inside DoAction

src/game/GameView.cpp

@@ -1490,7 +1490,6 @@ void GameView::NotifyNotificationsChanged(GameModel * sender)
 	}
 	notificationComponents.clear();
 
-
 	std::vector<Notification*> notifications = sender->GetNotifications();
 
 	int currentY = YRES-23;

src/interface/Button.cpp

@@ -151,10 +151,9 @@ void Button::OnMouseUp(int x, int y, unsigned int button)
 
     if(isButtonDown)
     {
+	    isButtonDown = false;
 		DoAction();
     }
-
-    isButtonDown = false;
 }
 
 void Button::OnMouseClick(int x, int y, unsigned int button)