RTC: add notion of 'quality' for different time sources

Allow use of mesh based time until a GPS time arrives

src/gps/NMEAGPS.cpp

@@ -45,7 +45,7 @@ The Unix epoch (or Unix time or POSIX time or Unix timestamp) is the number of s
         t.tm_mon = d.month() - 1;
         t.tm_year = d.year() - 1900;
         t.tm_isdst = false;
-        perhapsSetRTC(t);
+        perhapsSetRTC(RTCQualityGPS, t);
 
         return true;
     } else