Ragged CSV import

I have received a requirement for the ability to import ragged CSV
files, i.e. files that contain variable numbers of columns per row. The
requirement is that extra columns would be ignored and missing columns
filled with NULL. The client wanting this has wrestled with some
preprocessors to try to get what they want, but they would feel happier
with this built in. This isn't the first time I have received this
request since we implemented CSV import. People have complained on
numerous occasions about the strictness of the import routines w.r.t.
the number of columns.

I don't think that providing a CSV import mode for reading these files
will be very difficult or invasive. If it's not acceptable, I will
provide it to the client as a patch, and I will be retrofitting it to
8.4 anyway. But I think it's not an unreasonable request.

Thoughts?

cheers

andrew