message: fixed ostream output
diff: @@ -145,7 +145,7 @@ template <typename T>
  void WriteBinaryOrASCII(std::ostream &os, std::vector<char> &buf, const T &val,
  const char *suffix, VTKFormat format)
  {
  - if (format == VTKFormat::ASCII) { out << val << suffix; }
  + if (format == VTKFormat::ASCII) { os << val << suffix; }
  else { bin_io::AppendBytes(buf, val); }
  }
  