def initialize(host = nil, user = nil, passwd = nil, acct = nil)
      super()
      @binary = true
      @passive = false
      @debug_mode = false
      @resume = false
      @sock = NullSocket.new
      @logged_in = false
      @open_timeout = nil
      @read_timeout = 60
      if host
        connect(host)
        if user
          login(user, passwd, acct)
        end
      end
    end
Creates and returns a new +FTP+ object. If a +host+ is given, a connection
is made. Additionally, if the +user+ is given, the given user name,
password, and (optionally) account are used to log in.  See #login.