/// <summary>
 /// Removes a Particle.
 /// </summary>
 /// <param name="particle">The Particle to be removed.</param>
 internal static void Remove(ParticleObject particle)
 {
     if (particles.Contains(particle))
     {
         particles.Remove(particle);
     }
 }
 /// <summary>
 /// Adds a ParticleObject to be managed.
 /// </summary>
 /// <param name="particle">The Particle to be managed.</param>
 internal static void Add(ParticleObject particle)
 {
     particles.Add(particle);
 }