Add logic to reveal cloaked units, when they are only units left.

I'm not sure about IPositionable check but that was the easiest way to
get it ignore upgrades, generals powers and player actor.

OpenRA.Mods.Common/Traits/Cloak.cs

@@ -58,6 +58,9 @@ public class CloakInfo : ConditionalTraitInfo
 		[GrantedConditionReference]
 		[Desc("The condition to grant to self while cloaked.")]
 		public readonly string CloakedCondition = null;
+
+		[Desc("This units uncloaks if only units of the player are cloakable.")]
+		public readonly bool UncloakWhenAlone = true;
 
 		public override object Create(ActorInitializer init) { return new Cloak(this); }
 	}
@@ -187,6 +190,9 @@ public bool IsVisible(Actor self, Player viewer)
 			if (!Cloaked || self.Owner.IsAlliedWith(viewer))
 				return true;
 
+			if ((Info.UncloakWhenAlone && !self.World.Actors.Where(a => a.Owner == self.Owner && a.IsInWorld && a.TraitsImplementing<IPositionable>().Any() && !a.TraitsImplementing<Cloak>().Where(t => !t.IsTraitDisabled).Any()).Any()))
+				return true;
+
 			return self.World.ActorsWithTrait<DetectCloaked>().Any(a => !a.Trait.IsTraitDisabled && a.Actor.Owner.IsAlliedWith(viewer)
 				&& Info.CloakTypes.Overlaps(a.Trait.Info.CloakTypes)
 				&& (self.CenterPosition - a.Actor.CenterPosition).LengthSquared <= a.Trait.Info.Range.LengthSquared);