Code managing language in URLs and redirection is moved from website
to http_routing. Override of _dispatch in website now consists in adding
website to the request.
url_for and is_multilang_url tools methods are also moved from website
to http_routing.ir_http as those are required for the moved code.
Some renaming is performed on request attributes previously added in
website. Indeed as website keyword may be misleading now a renaming
has been performed to better understand them :
* request.website_enabled -> request.is_frontend
* request.website_multilang -> request.is_frontend_multilang
* request.httprequest.cookies.get('website_lang') -> ('frontend_lang')
* first_pass variable in _dispatch is replaced by a new attribute of
request, routing_iteration, that is the number of routing iterations
currently done