message: Add language suffix property for to_json
diff: @@ -236,6 +236,18 @@ ResultSet::to_JSON()
  else if (ans_str[0] == '"')
  {
  if (ans_str.find("\"^^<") == string::npos)
  + {
  + if (ans_str.find("\"@") != string::npos)
  + {
  + //for language string
  + ans_type = "literal";
  + string data_type = ans_str.substr(ans_str.rfind("@")+1, ans_str.length());
  + ans_str = ans_str.substr(1, ans_str.rfind('"') - 1);
  + _buf << "\"" + this->var_name[j].substr(1) + "\": { ";
  + _buf << "\"type\": \"" + ans_type + "\", \"lang\": \"" + data_type + "\", \"value\": " + Util::node2string((string("\"") + ans_str + "\"").c_str()) + " }";
  + list_empty = false;
  + }
  + else
  {
  //no has type string
  ans_type = "literal";
  @@ -244,6 +256,7 @@ ResultSet::to_JSON()
  _buf << "\"type\": \"" + ans_type + "\", \"value\": " + Util::node2string((string("\"") + ans_str + "\"").c_str()) + " }";
  list_empty = false;
  }
  + }
  else
  {
  string data_type = "";
  