handle vis formats as argument

Author: andreiamatuni

shell.go

@@ -677,10 +677,12 @@ func (s *Shell) ObjectPut(obj *IpfsObject) (string, error) {
 	return out.Hash, nil
 }
 
-func (s *Shell) DiagNet() ([]byte, error) {
+func (s *Shell) DiagNet(format string) ([]byte, error) {
 	var result = new(bytes.Buffer)
 
 	req := s.newRequest("diag/net")
+	req.Opts["vis"] = format
+
 	resp, err := req.Send(s.httpcli)
 	if err != nil {
 		return []byte{}, err