Add new scene controller with touch display example.

Upgraded RF24 to latest version which supports SoftSPI. 
Added DigitalIO and UTFT libraries to support the new example.
Fix problem reported in RelayWithButtonActuator example.

libraries/DigitalIO/examples/DigitalPinConfigToggle/DigitalPinConfigToggle.ino

@@ -0,0 +1,18 @@
+// Demo of config() and fast toggle() function.
+#include <DigitalIO.h>
+
+// Class with compile time pin number.
+DigitalPin<13> pin13;
+
+void setup() {
+  // Set mode to OUTPUT and level LOW.
+  pin13.config(OUTPUT, LOW);
+}
+void loop() {
+  // toggle is a two byte instruction that executes
+  // in two cycles or 125 ns on a 16 MHz CPU
+  pin13.toggle();
+  delay(100);
+  pin13.toggle();
+  delay(400);
+}