Generate IBAN from BBAN und country
Returns null if IBAN can't be generated, i.e. provided values are faulty or BBAN+country is invalid (if param 'validate' is true)
Account number with up to 10 digits
German BLZ with 8 digits
IBAN or null if invalid
Generate IBAN from BBAN und country
Returns null if IBAN can't be generated, i.e. provided values are faulty or BBAN+country is invalid (if param 'validate' is true)