Refactor building power-down and Invulnerable effect. Introduces render bugs on state change (effects appearing/dissapearing a frame too late)

OpenRa.Game/Effects/InvulnEffect.cs

@@ -0,0 +1,30 @@
+using System.Collections.Generic;
+using OpenRa.Game.Graphics;
+using OpenRa.Game.Traits;
+
+namespace OpenRa.Game.Effects
+{
+	class InvulnEffect : IEffect
+	{
+		Actor a;
+		IronCurtainable b;
+
+		public InvulnEffect(Actor a)
+		{
+			this.a = a;
+			this.b = a.traits.Get<IronCurtainable>();
+		}
+
+		public void Tick()
+		{
+			if (a.IsDead || b.GetDamageModifier() > 0)
+				Game.world.AddFrameEndTask(w => w.Remove(this));
+		}
+
+		public IEnumerable<Renderable> Render()
+		{
+			foreach (var r in a.Render())
+				yield return r.WithPalette(PaletteType.Invuln);
+		}
+	}
+}