Minor: add explicit default constructor.

library/include/mobilisis/spec_days.h

@@ -4,10 +4,12 @@
 class ATBSpecialDays
 {
 public:
+    explicit ATBSpecialDays() = default;
 	int ped_id;
 	std::string ped_label;
 	std::string ped_date_start;
 	std::string ped_date_end;
-	int ped_period_special_day_id;
+    int ped_period_special_day_id;
+    int ped_payment_option_id;
 	int ped_year;
-};
+};