This function negotiates the clients preferred language based on its
Accept-Language HTTP header. The qualifier is recognized and languages
without qualifier are rated highest. The qualifier will be decreased by
10% for partial matches (i.e. matching primary language).
Parameters
supported
array containing the supported languages as values
result
will be filled with an array containing the negotiation results
Return Values
Returns the negotiated language or the default language (i.e. first array entry) if none match.