Add a "change date/time notation" / "timezone" checkbox when changing site languages

[NekoJonez]

When I install WP, I usually do it in English. Yet, for some cases I have to change the locale to Dutch.

Now, I notice that the timezone and datetime notation stays in the old locale. Which is understandable... We don't want to force it on the user. That's why I'm suggesting that we add a checkbox or two so the user has the choice to also change the datetime/timezone setting to the locale default if they change.

It would make things a bit more flexible.