Support location in addition to ISO 3166-2 codes as region

In Spain we have national and regional holidays that can be covered by [ISO 3166-2:ES](https://en.wikipedia.org/wiki/ISO_3166-2:ES) codes but also 2 days of local holidays. And by local I mean holidays different by location not province. i.e. a Granada, Málaga or Seville holiday is not for the whole province but just for the city.

I think we must use ISO 3166 codes for regions that are covered but for smaller divisions accept the complete localized name of the location. Holidays by regions smaller and/or not in ISO 3266 codes could be the case in other countries. At least it is for Spain.
region | meaning
--|--
AN | for Andalusia autonomous community [ISO 3166-2:ES](https://en.wikipedia.org/wiki/ISO_3166-2:ES)
GR | for Granada province [ISO 3166-2:ES](https://en.wikipedia.org/wiki/ISO_3166-2:ES)
MA | for Málaga province [ISO 3166-2:ES](https://en.wikipedia.org/wiki/ISO_3166-2:ES)
SE | for Seville province [ISO 3166-2:ES](https://en.wikipedia.org/wiki/ISO_3166-2:ES)
Granada | for Granada city (proposed)
Málaga | for Málaga city (proposed)
Sevilla | for Seville city (proposed)

But I don't know if the region parameter can handle safely UTF-8 and spaces present in some location's name.

Start by tracing how the region parameter is parsed and how holiday regions are represented. Check whether UTF-8 names and spaces are already supported, then compare the proposed city names with the existing ISO 3166-2 handling. Done means local locations can be represented safely without breaking current ISO region codes, with behavior covered by tests.

Written by the indexing model from the issue text.