GravityExport field: ListField

The list field (ListField) is a bit of an annoying field to export. The reason for this is that a user can import multiple values, but every entry only has one row. To make matters worse, you can actually have multiple columns for this field, and add values to all those columns!

For GravityExport, we combine all values in to one (or more) columns and let those values be stacked via a new line (soft return, \n ).