Make sure hybrid evaluation does not get in the way of `order_by`.
There is probably a better way to handle this internally, i.e. we could probably make internal version
of `with_order` which does twice the work:

```
  ord <- order(order_by)
  undo <- match(seq_along(order_by), ord)
```

But I guess it is not high on the priority list, make it work is higher.

closes #169