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/AutoTarget.cs

@@ -111,11 +111,21 @@ namespace OpenRA.Mods.RA
 
 			var inRange = self.World.FindUnitsInCircle(self.CenterLocation, (int)(Game.CellSize * range));
 
-			return inRange
-				.Where(a => a.AppearsHostileTo(self))
-				.Where(a => !a.HasTrait<AutoTargetIgnore>())
-				.Where(a => attack.HasAnyValidWeapons(Target.FromActor(a)))
-				.ClosestTo( self.CenterLocation );
+			if (self.Owner.HasFogVisibility()) {
+				return inRange
+					.Where(a => a.AppearsHostileTo(self))
+					.Where(a => !a.HasTrait<AutoTargetIgnore>())
+					.Where(a => attack.HasAnyValidWeapons(Target.FromActor(a)))
+					.ClosestTo( self.CenterLocation );
+			}
+			else {
+				return inRange
+					.Where(a => a.AppearsHostileTo(self))
+					.Where(a => !a.HasTrait<AutoTargetIgnore>())
+					.Where(a => attack.HasAnyValidWeapons(Target.FromActor(a)))
+					.Where(a => self.Owner.Shroud.IsTargetable(a))
+					.ClosestTo( self.CenterLocation );
+			}
 		}
 	}