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/DigitalPinShiftOut/DigitalPinShiftOut.ino

@@ -0,0 +1,39 @@
+// Scope test for fast shiftOut function.
+#include <DigitalIO.h>
+
+// Create clockPin in output mode with inital level LOW.
+DigitalPin<12> clockPin(OUTPUT, LOW);
+
+// Create dataPin in output mode with inital level HIGH.
+DigitalPin<13> dataPin(OUTPUT, HIGH);
+
+//------------------------------------------------------------------------------
+// Time to send one bit is ten cycles or 625 ns for 16 MHz CPU.
+inline __attribute__((always_inline))
+void sendBit(uint8_t bit, uint8_t data) {
+  dataPin = data & (1 << bit);
+  clockPin = 1;
+  // may want a nop here - clock pulse is 125 ns wide
+  clockPin = 0;
+}
+//------------------------------------------------------------------------------
+// Time to send one byte is 5 usec.
+void shiftOut(uint8_t bits) {
+  sendBit(7, bits);
+  sendBit(6, bits);  
+  sendBit(5, bits);  
+  sendBit(4, bits);
+  sendBit(3, bits);
+  sendBit(2, bits);
+  sendBit(1, bits); 
+  sendBit(0, bits); 
+}
+//------------------------------------------------------------------------------
+void setup() {
+  // Not used.
+}
+//------------------------------------------------------------------------------
+void loop() {
+  shiftOut(0X55);
+  delay(2);
+}