Re: [PATCH] Add roman support for to_number function

While playing with the patch I noticed that to_char(..., 'RN') doesn't
seem to be test-covered. I suggest adding the following test:

```
WITH rows AS (
    SELECT i, to_char(i, 'FMRN') AS roman
    FROM generate_series(1, 3999) AS i
) SELECT bool_and(to_number(roman, 'RN') = i) FROM rows;

 bool_and
----------
 t
```