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/Effects/GpsDot.cs

@@ -57,7 +57,7 @@ namespace OpenRA.Mods.RA.Effects
 			if (
 				self.IsInWorld
 				&& (watcher.Granted || watcher.GrantedAllies)
-				&& !self.Trait<HiddenUnderFog>().IsVisible(self)
+				&& !self.Trait<HiddenUnderFog>().IsVisible(self.World.RenderedShroud, self) // WRONG
 				&& (!self.HasTrait<Cloak>() || !self.Trait<Cloak>().Cloaked)
 				&& (!self.HasTrait<Spy>() || !self.Trait<Spy>().Disguised)
 				)