Update for Allow to delete all vouchers

Replaces !544 (closed)

closes #503 (closed)

Delete voucher function checks for two more conditions :-

• Is there any voucher for round off associated with the one being deleted?
• Is there a debit/credit note entry and thus any round off associated with it?

To make this easier a new fucntion voucherbininsert that fires the actual delete query and subsequent post delete queiries has been created.