/// <summary>
/// Removes the given background from the rendering engine
/// </summary>
/// <param name="bg">the background to remove</param>
public void removeBackground(Background bg)
{
bgs.Remove(bg);
}
/// <summary>
/// Adds the given background to the rendering engine (so it can be rendered)
/// </summary>
/// <param name="bg">The background to be added</param>
public void addBackground(Background bg)
{
bgs.Add(bg);
}