Make metric/imperial a user setting

[RoundOrange]

Currently, the metric/imperial option is hard coded in src/script.js. As measurement units can be a personal preference, or a user may have grown up learning one system, but now live in a country which uses another, please consider allowing the user to specify their preference.

Also, en_AU and en_NZ are listed in src/script.js as imperial countries. They most certainly are not and have not been for a long time. Please remove these countries from the imperial list.

[goldgoldfish]

en_CA should also be removed from the imperial group.

[vwbusguy]

I'm not sure how this is working now anyway? I'm in the USA with en_US and I'm still seeing metric measurements. Besides, I know plenty of people who live in the US who moved here from somewhere else that might prefer metric.

[ToeJet]

This would be a welcome option. Or possibly a dual display. I do some things like driving which I track in miles. Others like walking are tracked in km.

[kenherbert]

None of the locales currently hardcoded except en_US officially use imperial-derived measurements.