Support multiple capture traits in order targeter and script plumbing.

OpenRA.Mods.Common/Traits/CaptureManager.cs

@@ -40,6 +40,20 @@ namespace OpenRA.Mods.Common.Traits
 		public readonly bool PreventsAutoTarget = true;
 
 		public virtual object Create(ActorInitializer init) { return new CaptureManager(this); }
+
+		public bool CanBeTargetedBy(FrozenActor frozenActor, Actor captor, Captures captures)
+		{
+			if (captures.IsTraitDisabled)
+				return false;
+
+			// TODO: FrozenActors don't yet have a way of caching conditions, so we can't filter disabled traits
+			// This therefore assumes that all Capturable traits are enabled, which is probably wrong.
+			// Actors with FrozenUnderFog should therefore not disable the Capturable trait.
+			var stance = frozenActor.Owner.Stances[captor.Owner];
+			return frozenActor.Info.TraitInfos<CapturableInfo>()
+				.Any(c => c.ValidStances.HasStance(stance) &&
+				          captures.Info.CaptureTypes.Overlaps(c.Types));
+		}
 	}
 
 	public class CaptureManager : INotifyCreated, INotifyCapture, ITick, IPreventsAutoTarget