gen_relative_url

# File lib/rdoc/markup/to_html.rb, line 30
  def self.gen_relative_url(path, target)
    from        = File.dirname path
    to, to_file = File.split target

    from = from.split "/"
    to   = to.split "/"

    from.delete '.'
    to.delete '.'

    while from.size > 0 and to.size > 0 and from[0] == to[0] do
      from.shift
      to.shift
    end

    from.fill ".."
    from.concat to
    from << to_file
    File.join(*from)
  end