Journalize revenue action disabled

The journalize revenue action may be disabled even when created invoices exist. Billed balances are updated by the generate invoice action. Use this action to ensure that there is no over-billing if multiple invoices are created before journalizing. If the invoice is deleted before journalizing, the billed balance is reduced and revenue can be journalized. Billed and revenue balances are necessary to determine the correct offset entries to billed/unearned and earned/unbilled accounts.