Introducing per-player shrouds.

- Each player has their own shroud and their visibility does not extend outside of the shroud. 
- Units and buildings can no longer target other units outside of their visibility. Buildings can still be targetted if they have been explored.
- GPS will provide visibility in the fog-of-war.
- Spies that infiltrate radar domes will gain their victim's exploration and reset it on all clients (if the victim does not have GPS)

OpenRA.Mods.RA/Crates/HideMapCrateAction.cs

@@ -25,8 +25,7 @@ namespace OpenRA.Mods.RA
 		public override int GetSelectionShares (Actor collector)
 		{
 			// don't ever hide the map for people who have GPS.
-			var gpsWatcher = collector.Owner.PlayerActor.TraitOrDefault<GpsWatcher>();
-			if (gpsWatcher != null && (gpsWatcher.Granted || gpsWatcher.GrantedAllies))
+			if (collector.Owner.HasFogVisibility())
 				return 0;
 
 			return base.GetSelectionShares (collector);
@@ -36,7 +35,7 @@ namespace OpenRA.Mods.RA
 		{
 			base.Activate(collector);
 			if (collector.Owner == collector.World.LocalPlayer)
-				collector.World.WorldActor.Trait<Shroud>().ResetExploration();
+				collector.Owner.Shroud.ResetExploration();
 		}
 	}
 }