Adjust handling of year display in wallclock mode and company inauguration years

See: #657

src/cheat_gui.cpp

@@ -120,6 +120,7 @@ static int32_t ClickChangeDateCheat(int32_t p1, int32_t p2)
 		/* Shift cached dates. */
 		LinkGraphSchedule::instance.ShiftDates(new_econ_date - EconTime::CurDate());
 		ShiftVehicleDates(new_econ_date - EconTime::CurDate());
+		EconTime::Detail::period_display_offset -= (p1 - EconTime::CurYear().base());
 
 		EconTime::Detail::SetDate(new_econ_date, new_econ_date_fract);
 		UpdateOrderUIOnDateChange();