Automatic language detection

[BaumiCoder]

Short description:
If I visit the website white a non english browser, e.g. a german one, the website should automatically switch to this language. If the language isn't available on the website, english should be the default.

Location:
Everywhere on the website.

A special site is the subscribing page (documented here). A manual switch of the language does remove the url parameter, a automatic switch should avoid that.

Why have this:
Better accessibility for people without English skills, especially on the subscribing page.