Support for pain.001.003.03 and pain.008.003.02 (closes #11)

New features with the upgraded schema:

* Support for IBAN only (giving BIC is now optional)
* DirectDebit: Support for COR1
* CreditTransfer: Support for URGP (urgent payment)

BEWARE: Support for pain.001.002.03 and pain.008.002.02 is dropped!