#7 Field Order indicator

Hi,

I would like to suggest that you add a field order
function, that will indicate the file's field order,
much like the function

int dv_is_progressive (dv_decoder_t *dv);

The method might be

int dv_field_order(dv_decoder_t *dv);

return values:
-1: unknown
0: progressive
1: lower field first
2: upper field first

Thanks,
Jamie Strachan.