reinstate range circles; IRenderSelection allows arb. plugging in of these things

OpenRA.Mods.RA/RenderDetectionCircle.cs

@@ -0,0 +1,26 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2010 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made 
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see LICENSE.
+ */
+#endregion
+
+using System.Drawing;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.RA
+{
+	class RenderDetectionCircleInfo : TraitInfo<RenderDetectionCircle> { }
+	class RenderDetectionCircle : IRenderSelection
+	{
+		public void Render(Actor self)
+		{
+			self.World.WorldRenderer.DrawRangeCircle(
+				Color.FromArgb(128, Color.LimeGreen),
+				self.CenterLocation, self.Info.Traits.Get<DetectCloakedInfo>().Range);
+		}
+	}
+}