Use a better source of data

[ksandom]

At the moment, the data is pulled from the wikipedia edit page. This feels like a fragile way to do it.

Find a better way.

Eg the IANA database.

I've given this a quick pass, and this looks significantly more complicated than what the timezone2offset project is trying to achieve. So probably something downstream will be better.

[ksandom]

It would be worth spending some time on the timezone-list tag.