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

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -166,6 +166,8 @@ namespace OpenRA.Traits
 	public interface IVictoryConditions { }
 	public interface IBlocksBullets { }
 
+	public interface IRenderSelection { void Render(Actor self); }
+
 	public struct Target		// a target: either an actor, or a fixed location.
 	{
 		Actor actor;