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/Contrail.cs

@@ -91,8 +91,8 @@ namespace OpenRA.Mods.RA
 				var conPos = positions[i];
 				var nextPos = positions[i - 1];
 
-				if (self.World.LocalShroud.IsVisible(conPos.ToCPos()) ||
-					self.World.LocalShroud.IsVisible(nextPos.ToCPos()))
+				if (self.World.RenderedShroud.IsVisible(conPos.ToCPos()) ||
+					self.World.RenderedShroud.IsVisible(nextPos.ToCPos()))
 				{
 					Game.Renderer.WorldLineRenderer.DrawLine(conPos.ToFloat2(), nextPos.ToFloat2(), trailStart, trailEnd);