Add support for several guesses at user region

[phcoder]

This is meant for discussion, not necessarily for merge

[micolous]

It sounds like the proposal is:

• Metrodroid would provide a list of regions, rather than a single region. All cards matching one of those regions would be considered "nearby".
• Metrodroid would consider all active SIMs as sources of data in the device, not just the primary SIM.
• Metrodroid would always consider the locale setting as a source of data, not just when a device doesn't have a cellular network connection.

I originally avoided using the device locale because many devices were set to en-gb or en-us, even when they're not ever used in those countries, and it could be perceived as some sort of bias on the developers' part (when in fact, we're using device preferences). The same may be true for other languages which are spoken in multiple countries/regions.

Evaluating that again now for the current versions of Android and iOS:

• Current versions of Android and iOS provide much more fine-grained locale settings, in part because many carriers require devices have an option for their local dialect. As a result, it's more likely to match user intent – a user in Australia is more likely to use en-au than en-gb.

• For those travelling internationally, a user having their home country still show up is not unexpected (and it would probably show up anyway if using international roaming).

• For those who intentionally set their device language to a dialect other than the one spoken locally (eg: using en-us in UK), that's too hard to fix. 😅

• For those who set their device language to a language other than an official language in the country they reside, this change could still muddy the "nearby" property (eg: an English speaker in Switzerland may see UK or US as "nearby" options, if they did not pick "English (Switzerland)" – and it may not even be available), but it is not entirely unexpected.

Overall though, I think this change is a net positive. 👍