Model Placeholder ?TableAlias not working on "Order"

The following does not work because Order is not replacing the Placeholder.

```
query := db.NewSelect().
  Model(&someSlice).
  Relation("Rel1").
  Relation("Rel2").
  Where("?TableAlias.field_name = ?", fieldValue).
  Order("?TableAlias.sort_field DESC")
```

Error:

`SQL logic error: no such column: ?TableAlias.sort_field (1)`