Finished EmitCargoOnSell

The broken Lint check is still a problem after all those years. This also does not work as suggested in the empty trait. During selling it destroys the cargo so you can't just queue an Unload activity. You can't even enumerate through all passengers without hitting crashes. However, unloading just the first passenger is good enough for Red Alert's single-manned pillboxes.
It would be a bit nicer to invert this:

```csharp
if (!Info.EjectOnSell || cargo == null)
    return;

while (!IsEmpty(self))
    ForceEjectPassenger(self);
```

You will need to be careful about doing the right thing if the adjacent cells are blocked.