automatically update internal structures on setTime and setToCompilerTime

This allows the user to immediately access correct internal values (myRTC.weekday, myRTC.minute, etc...)

```
  myRTC.setTime(23, 59, 59, 99, myRTC.dayOfMonth, myRTC.month, myRTC.year);
  previousDay = myRTC.weekday;
```

Updated Example3 to make use of this feature

Author: oclyke

libraries/RTC/examples/Example3_Test_RTC/Example3_Test_RTC.ino

@@ -17,15 +17,13 @@ void setup()
   delay(10);
   Serial.println("Artemis RTC Testing");
 
-  // Manually set RTC date and time
-  myRTC.setTime(23, 59, 59, 0, 1, 1, 20); // Set to 1 second before midnight
-  myRTC.getTime();
+  // Manually set RTC date and time to the start of 2020 so that myRTC contains valid times
+  myRTC.setTime(23, 59, 59, 0, 1, 1, 20); // Set to 1 second before midnight Jan 1
 }
 
 void loop()
 {
-  myRTC.setTime(23, 59, 59, 99, myRTC.dayOfMonth, myRTC.month, myRTC.year); // Manually set RTC
-  myRTC.getTime();
+  myRTC.setTime(23, 59, 59, 99, myRTC.dayOfMonth, myRTC.month, myRTC.year); // Manually set RTC 1/100th of a second from the next day
   previousDay = myRTC.weekday;
   delay(11); //Allow us to roll from midnight the night before to the new day
 

libraries/RTC/src/RTC.cpp

@@ -66,6 +66,7 @@ void APM3_RTC::setTime(uint8_t hour, uint8_t min, uint8_t sec, uint8_t hund, uin
   hal_time.ui32Hundredths = hund;
 
   am_hal_rtc_time_set(&hal_time); //Initialize the RTC with this date/time
+  getTime();
 }
 
 //Takes the time from the last build and uses it as the current time
@@ -85,6 +86,7 @@ void APM3_RTC::setToCompilerTime()
   hal_time.ui32Hundredths = 00;
 
   am_hal_rtc_time_set(&hal_time); //Initialize the RTC with this date/time
+  getTime();
 }
 
 void APM3_RTC::setEpoch(uint32_t ts)