Accept int put_code

[Wooble]

In read_record_public, when a list of put_codes is given, these are currently joined together as strs, but the API returns these codes as ints. It's not a huge burden to convert put_codes I got from one call to str before making another call for full details of the works, but it would be convenient to just pass in the list of ints I pull from the other data.