When converting fields that use filtered text, format column gets skipped, update order gets messed up.

First, thanks for this module, it's pretty useful. I think I found a bug where if you're converting nodes that have fields that use filtered text, the ordering in the update gets messed up. At least, this seems to be what is happening. The format is stored in another column in the table, but the 'multiple' flag is not set, so the column gets skipped, and then the wrong values get updated in the database. I've attached a diff of what I think is working for now. I am on a deadline so I do not currently have the time to think about all the cases, but I wanted to report this issue and show the diff in case someone is able to look at it in the meantime. In the diff, I am just tricking it into using the multiple column case, when it finds a column called 'format'.

Ian