Support FIPS region codes

[tobiasschuerg]

It would be great if support for FIPS region codes would be added so that also those codes would be recognized.

A random example: PL-72 is actually PL-02 See https://en.wikipedia.org/wiki/List_of_FIPS_region_codes_(P%E2%80%93R)#PL:_Poland and https://en.wikipedia.org/wiki/ISO_3166-2:PL.

This should be doably by a simple mapping table.

[tobiasschuerg]

This is the mapping I use for poland:

subdivision_mapping = {
# iso codes before 2018
    "PL-DS": "PL-02",
    "PL-KP": "PL-04",
    "PL-LB": "PL-08",
    "PL-LD": "PL-10",
    "PL-LU": "PL-06",
    "PL-MA": "PL-12",
    "PL-MZ": "PL-14",
    "PL-OP": "PL-16",
    "PL-PD": "PL-20",
    "PL-PK": "PL-18",
    "PL-PM": "PL-22",
    "PL-SK": "PL-26",
    "PL-SL": "PL-24",
    "PL-WN": "PL-28",
    "PL-WP": "PL-30",
    "PL-ZP": "PL-32",
# FIPS codes
    "PL-72": "PL-02",
    "PL-73": "PL-04",
    "PL-76": "PL-08",
    "PL-74": "PL-10",
    "PL-75": "PL-06",
    "PL-77": "PL-12",
    "PL-78": "PL-14",
    "PL-79": "PL-16",
    "PL-81": "PL-20",
    "PL-80": "PL-18",
    "PL-82": "PL-22",
    "PL-84": "PL-26",
    "PL-83": "PL-24",
    "PL-85": "PL-28",
    "PL-86": "PL-30",
    "PL-87": "PL-32"
}

I'd prefer to have this mapping inside the library for all regions (where it makes sense), so that pycountry.subdivisions.get(code='PL-02') and pycountry.subdivisions.get(code='PL-DS') and pycountry.subdivisions.get(code='PL-72') all return the same subdivision.

[nschimmoller]

@tobiasschuerg The intention of this library is to be a python wrapper for ISO Codes and unfortunately FIPS falls outside of that. So this will definitely not make our development roadmap but if you'd like to submit a PR feel free :)