ISO 4217 currency codes

[donmendelson]

SBE depends on ISO 4217 for currency codes, among other standards. ISO 4217:2008 mentioned in the spec has been revised by ISO 4217:2015.

[kleihan]

It is probably good to have SBE 1.0 support ISO 4217:2015 (and not only the newer versions of SBE). Could this fall under a patch version, e.g. v1.0.1?

[donmendelson]

This issue is errata for version 1.0.