API to get locale date format

Hi,

AFAIK, at the moment there's no standard way to get the system locale date
format. There are some hacks that can be used to infer it, but, well, they
are just hacks.

As it is not possible to change the representation format of date, time,
etc. input types [1], at least the system locale's date format should
somehow be exposed via an API.

[1]: Ideally, not only the locale's date (and other value/unit) format
should be exposed via an API, but the representation format of date, time,
etc. fields should be customizable via API/attributes.

Best regards,
Behrang Saeedzadeh