Many changes - tidying up the extensions interfaces.

Updating the GPIO command - new command - allreadall
ScrollPhat code
max31855 code (tested with adafruit breakout board)
more tests
updated rht03 code

Raspberry Pi v3 support.

wiringPi/sr595.c

@@ -105,5 +105,5 @@ int sr595Setup (const int pinBase, const int numPins,
   pinMode (clockPin, OUTPUT) ;
   pinMode (latchPin, OUTPUT) ;
 
-  return 0 ;
+  return TRUE ;
 }