Add CLASS support for IIF Export of accounting batches

I would like to add support for specifying a CLASS that would be associated with transactions that are created for the IIF export.

Currently the Account Type Code is associated with the Account record and is used to fill in the AccountType when an IIF is generated. I would propose that a "Financial Type Code" be be added to the Financial Type. If that field has been filled in then it would be used to specify the CLASS in the IIF file that is generated via the IIF export.

If this is the type of thing that would be acceptable I would be happy to contribute a patch but if there is a different way would be more acceptable to the core contributors please point me in the right direction and I'll put together a patch.