Enable use of CSV-text with double quote escaped by duplicate double quote

We use CSV-files with articles. The description can contain a double quote, such as:

“This is an article”

Also, the description itself can contain a double quote, such as:

“Slang R12 96"” 2,43m geel"

This last format is currently not handled by csvtable.

It would be helpful when they could be processed too.