Remove unused sub
Bug fixes for content negotation related headers

Charsets and languages are canonicalized for comparison and for return from
the negotiator class.

The code now follow RFC-2616 for Accept-Charset:

    If no "*" is present in an Accept-Charset field, then all character sets
    not explicitly mentioned get a quality value of 0, except for ISO-8859-1,
    which gets a quality value of 1 if not explicitly mentioned.

Added AcceptCharset and AcceptLanguage classes to support this work.