def list(*args, &block) # :yield: line
      cmd = "LIST"
      args.each do |arg|
        cmd = cmd + " " + arg.to_s
      end
      if block
        retrlines(cmd, &block)
      else
        lines = []
        retrlines(cmd) do |line|
          lines << line
        end
        return lines
      end
    end
Returns an array of file information in the directory (the output is like
`ls -l`).  If a block is given, it iterates through the listing.