add support for hardware rtc, not sure if this version won't crash

include/rtc.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include "constants.h"
+#include <ESP32Time.h>
+#include <RX8010SJ.h>
+
+extern bool rtcset;
+extern bool NTPupdated;
+
+extern ESP32Time rtc;
+extern bool rx_rtc_avail;
+extern RX8010SJ::Adapter rx_rtc;
+
+void timeToDateTime(time_t t, struct RX8010SJ::DateTime* dateTime);
+time_t dateTimeToTime(const struct RX8010SJ::DateTime* dateTime);
+
+void sync_to_rx_rtc(int32_t offset = 0);
+void sync_from_rx_rtc(int32_t offset = 0);