cargo: Passenger trait for things that can enter transports

OpenRa.Game/OpenRa.Game.csproj

@@ -215,6 +215,7 @@
     <Compile Include="Traits\MineImmune.cs" />
     <Compile Include="Traits\Minelayer.cs" />
     <Compile Include="Traits\LimitedAmmo.cs" />
+    <Compile Include="Traits\Passenger.cs" />
     <Compile Include="Traits\Repairable.cs" />
     <Compile Include="Traits\Reservable.cs" />
     <Compile Include="Traits\SquishByTank.cs" />

OpenRa.Game/Orders/UnitOrderGenerator.cs

@@ -81,6 +81,7 @@ namespace OpenRa.Game.Orders
 					else
 						return Cursor.MoveBlocked;
 				case "Enter": return Cursor.Enter;
+				case "EnterTransport": return Cursor.Enter;
 				case "Deliver": return Cursor.Enter;
 				case "Infiltrate": return Cursor.Enter;
 				case "Capture": return Cursor.Capture;

OpenRa.Game/Traits/Passenger.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using OpenRa.Game.Traits.Activities;
+
+namespace OpenRa.Game.Traits
+{
+	class Passenger : IOrder
+	{
+		public Passenger(Actor self) { }
+
+		public Order IssueOrder(Actor self, int2 xy, MouseInput mi, Actor underCursor)
+		{
+			if (mi.Button != MouseButton.Right) 
+				return null;
+
+			if (underCursor == null || underCursor.Owner != self.Owner)
+				return null;
+
+			var cargo = underCursor.traits.GetOrDefault<Cargo>();
+			if (cargo == null || cargo.IsFull(underCursor))
+				return null;
+
+			var umt = self.traits.WithInterface<IMovement>().First().GetMovementType();
+			if (!underCursor.Info.PassengerTypes.Contains(umt))
+				return null;
+
+			return new Order("EnterTransport", self, underCursor, int2.Zero, null);
+		}
+
+		public void ResolveOrder(Actor self, Order order)
+		{
+			if (order.OrderString == "EnterTransport")
+			{
+				self.CancelActivity();
+				self.QueueActivity(new Move(order.TargetActor, 0));
+				// todo: actually enter the transport
+			}
+		}
+	}
+}