Will ISO-3166-3 be supported?

[jakewilliami]

I notice you have a data file for ISO-3166-3, but I can't (for example) find SU. Are you planning on supporting these?

[biter777]

The code was removed from ISO 3166-1 in 1992.
Explain in more detail for what purpose you need to include obsolete code?

[jakewilliami]

I'm pulling top level domains from the IANA TLD database, and if they are country-code TLDs, I am using your library to cross-reference using country code.

SU was just an example, but in general, support for ISO 3166-3 might be useful if you need to reference countries that have been removed from ISO 3166-1. It looks like you already have the data but it's not yet implemented in the library.

[biter777]

@jakewilliami Could you do this PR?