Restructured BF.change_languages() to separate BF.load_language().

Other improvements too.
Restructured BF.get_preferred_supported_lang() and added BF.get_acceptable_langs().
Added BF.get_recent_and_acceptable_langs().
If a search returns nothing, check to see if the query is actually a verse reference in a language the user might actually use.

We keep track of recently used languages and take into consideration the client's Accept-Language header.
Catch regex errors when parsing for the url_suffix.