Add nil checks for connect-options dialer and logger to prevent
nil-pointer panics when Connect is called without a DialerConnectOption
or LoggerOption. Add package and NewConnector godoc comments.
Add 10 unit tests covering construction, Init metadata parsing,
Connect success/reject/dial-error paths, nil dialer, nil logger,
and the reject conn stub.
ginuerzh
4efb4b9974