Support BBAN verification using ECBS summary of european and non-european domestic account numbers

[marcwrobel]

ECBS has a document that explain BBAN structure in detail : https://www.ecbs.org/Download/Tr201v3.9.pdf. Use it to verify BBAN structures (as long as it does not depend on external data).

[marcwrobel]

See also : https://en.wikipedia.org/wiki/International_Bank_Account_Number#National_check_digits.

[marcwrobel]

This verification will not be mandatory (e.g. it will not prevent Iban creation nor validation), at least for the time being. Some people consider the IBAN check digit verification enough to catch most input errors and I tend to agree with them.

It's unclear for the time being if this feature will be directly accessible from the IBAN API or if will be just a loose support for people that are interested by such a feature.