Add country validation for BIC

[LuukGubbels]

Currently, when validating an IBAN a check is ran to see if the country code is valid.

This is not done for BIC and leads to faulty behaviour. When executing

stdnum.bic.is_valid("MULTIPLE")

the function will return True, since the string matches the regex ^[A-Z]{6}[0-9A-Z]{2}([0-9A-Z]{3})?$.
In this string "IP" should be the country code, but this does not exist and hence the is_valid function should return False instead.

[arthurdejong]

Hi @LuukGubbels,

Thanks for reporting this. I've added validation of the country code part in 843bbec.

According to Wikipedia, the country code is ISO 3166-1 alpha-2 with an exception for Kosovo.

I've had a look at whether the IBAN country codes can also be used for BIC but it turns out that there are a large number (100+) of countries that use BICs but not IBANs.