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)

mods/ra/rules/system.yaml

@@ -188,6 +188,7 @@ Player:
 	DebugResourceOre:
 	DebugResourceOreCapacity:
 	GpsWatcher:
+	Shroud:
 	BaseAttackNotifier:
 
 World: