Add a metatable with ordered column names

[ubaldus]

To allow column order reconstruction after a query.

[agentzh]

@ubaldus I don't quite follow your patch. It does not make sense to add the cols table as the metatable to rows. It's just logically wrong.

[ubaldus]

Hi Agentzh, the idea is to have an easy and quick access to the column names as retrieved by the sql query, is there a more efficient way to achieve the same result?

[agentzh]

@ubaldus I still do not understand your intention. Maybe you should elaborate with concrete examples?