use RepairIndicator rather than renderer hack

OpenRa.Game/Effects/RepairIndicator.cs

@@ -0,0 +1,27 @@
+using System.Collections.Generic;
+using OpenRa.Game.Graphics;
+using OpenRa.Game.Traits;
+
+namespace OpenRa.Game.Effects
+{
+	class RepairIndicator : IEffect
+	{
+		int framesLeft = (int)(Rules.General.RepairRate * 25 * 60 / 2);
+		Actor a;
+		Animation anim = new Animation("select");
+
+		public RepairIndicator(Actor a) { this.a = a; anim.PlayRepeating("repair"); }
+
+		public void Tick()
+		{
+			if (--framesLeft == 0 || a.IsDead)
+				Game.world.AddFrameEndTask(w => w.Remove(this));
+		}
+
+		public IEnumerable<Renderable> Render()
+		{
+			yield return new Renderable(anim.Image, 
+				a.CenterLocation - .5f * anim.Image.size, PaletteType.Chrome);
+		}
+	}
+}