categorize traits better

OpenRa.Game/Traits/Modifiers/InvisibleToOthers.cs

@@ -0,0 +1,15 @@
+using System.Collections.Generic;
+
+namespace OpenRa.Traits
+{
+	class InvisibleToOthersInfo : StatelessTraitInfo<InvisibleToOthers> { }
+
+	class InvisibleToOthers : IRenderModifier
+	{
+		public IEnumerable<Renderable> ModifyRender(Actor self, IEnumerable<Renderable> r)
+		{
+			return self.World.LocalPlayer == self.Owner
+				? r : new Renderable[] { };
+		}
+	}
+}