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.Game/Traits/Player/DeveloperMode.cs

@@ -77,7 +77,7 @@ namespace OpenRA.Traits
 					{
 						DisableShroud ^= true;
 						if (self.World.LocalPlayer == self.Owner)
-							self.World.LocalShroud.Disabled = DisableShroud;
+							self.World.RenderedShroud.Disabled = DisableShroud;
 						break;
 					}
 				case "DevPathDebug":
@@ -88,7 +88,7 @@ namespace OpenRA.Traits
 				case "DevGiveExploration":
 					{
 						if (self.World.LocalPlayer == self.Owner)
-							self.World.WorldActor.Trait<Shroud>().ExploreAll(self.World);
+							self.World.LocalPlayer.Shroud.ExploreAll(self.World);
 						break;
 					}
 				case "DevUnlimitedPower":