Fix the zero account balance with items listed as still due

None of the categories really fit. It would be helpful if credits were applied automatically. For example, if a student has a credit with transaction code "registration fee" it should automatically be applied to the registration fee when the student registers. If a student pre-pays tuition then the payment with a tuition transaction code should automatically apply to the tuition as it is posted. It makes no sense that an account should have a zero balance and that items are marked as still unpaid.