Ticket #677 (new new feature)

Description

We need 404s. As is, page not found redirects the front page which is bad behaviour: - when you try to go to a page that's not there, you don't expect the front page, you expect "not found" - search engines will see lots of double pages where there should in fact be "not found"

It's not just a question of having the "right" behaviour it's also a question of taking the opportunity to help people. Say you're surfing the faq pages and you try to go for one in a language that's not present (modifying the url, perhaps, or following a slightly wrong link). Instead of redirecting people, we can present them with a 404 and then some helpful links to pages they might have wanted to go to (checking the url to see if there are close matches). This will be much more helpful to people than seeing the front page.