Fix cargo loading/unloading.

- Fix the unloading subcell bug, letting us have units move to directly adjacent cells.
- Have the cursor change to a deploy-blocked cursor if the transport can't unload due to terrain type.
- Add RenderTransport for transport door opening.
- Remove turning/opening in general.

OpenRA.Mods.RA/Missions/Allies04Script.cs

@@ -285,7 +285,7 @@ namespace OpenRA.Mods.RA.Missions
 				self.QueueActivity(new Move.Move(reinforcementsEntryPoint.Location));
 				self.QueueActivity(new RemoveSelf());
 			}));
-			lst.QueueActivity(new UnloadCargo(true));
+			lst.QueueActivity(new UnloadCargo(lst, true));
 			lst.QueueActivity(new Transform(lst, "lst.unselectable.nocargo") { SkipMakeAnims = true });
 		}
 
@@ -342,7 +342,7 @@ namespace OpenRA.Mods.RA.Missions
 			}));
 			lst.QueueActivity(new Move.Move(spyReinforcementsUnloadPoint.Location));
 			lst.QueueActivity(new Wait(10));
-			lst.QueueActivity(new UnloadCargo(true));
+			lst.QueueActivity(new UnloadCargo(lst, true));
 			lst.QueueActivity(new Transform(lst, "lst.unselectable.nocargo") { SkipMakeAnims = true });
 		}