Replace MoveIntoWorld with ReturnToCell/AssociateWithAirfield.

OpenRA.Mods.Common/Scripting/Properties/TransportProperties.cs

@@ -10,6 +10,7 @@
 #endregion
 
 using System.Linq;
+using Eluant;
 using OpenRA.Mods.Common.Activities;
 using OpenRA.Mods.Common.Traits;
 using OpenRA.Scripting;
@@ -35,7 +36,13 @@ namespace OpenRA.Mods.Common.Scripting
 		public int PassengerCount { get { return cargo.Passengers.Count(); } }
 
 		[Desc("Teleport an existing actor inside this transport.")]
-		public void LoadPassenger(Actor a) { cargo.Load(Self, a); }
+		public void LoadPassenger(Actor a)
+		{
+			if (!a.IsIdle)
+				throw new LuaException("LoadPassenger requires the passenger to be idle.");
+
+			cargo.Load(Self, a);
+		}
 
 		[Desc("Remove the first actor from the transport.  This actor is not added to the world.")]
 		public Actor UnloadPassenger() { return cargo.Unload(Self); }