BUGFIX: use correct relation for memType GROUP BY

After this has been merged into master, it makes sense for all users to regenerate records in the tables $FANNIE_ARCHIVE_DB.sumDiscountsByDay and $FANNIE_ARCHIVE_DB.sumMemTypeSalesByDay with the now correct numbers.  Not sure how best to approach this, logistically; an update?  I can create it, if folks thinks that's the best approach.