public void CleanTemporaryGameLists()//gameobject lists are cleaned up
{
GameDisplay.Children.Clear();
//lists are updated
EnemyProjectiles = EnemyProjectiles.Except(TemporaryEnemyProjectiles).ToList();
PlayerProjectiles = PlayerProjectiles.Except(TemporaryPlayerProjectiles).ToList();
Ufos = Ufos.Except(TemporaryUfos).ToList();
Walls = Walls.Except(TemporaryWalls).ToList();
Invaders = Invaders.Except(TemporaryInvaders).ToList();
//temporary lists are cleared
TemporaryWalls.Clear();
TemporaryPlayerProjectiles.Clear();
TemporaryInvaders.Clear();
TemporaryEnemyProjectiles.Clear();
TemporaryUfos.Clear();
}