w3m.rb $Id: w3m.rb 597 2005-10-18 21:03:12Z rubikitch $
--- W3M.w3m(url, options='-e')
invoke w3m.
--- W3M.html2txt(htmlstr, options='-e')
convert htmlstr to plain text.
--- W3M.source(url, options='-e')
get the source.