corrected Fwd/Rev LED logic in NmraDccMultiFunctionMotorDecoder example

added conditional compilation to use the newer Dcc.pin() method that used digitalPinToInterrupt() to determine the Ext Interrupt Number based on Arduino Pin to reduce confusion

examples/NmraDccAccessoryDecoder_1/NmraDccAccessoryDecoder_1.ino

@@ -7,6 +7,9 @@
 NmraDcc  Dcc ;
 DCC_MSG  Packet ;
 
+// Define the Arduino input Pin number for the DCC Signal 
+#define DCC_PIN     2
+
 struct CVPair
 {
   uint16_t  CV;
@@ -98,8 +101,14 @@ void setup()
 
   Serial.println("NMRA DCC Example 1");
   
-  // Setup which External Interrupt, the Pin it's associated with that we're using and enable the Pull-Up 
-  Dcc.pin(0, 2, 1);
+  // Setup which External Interrupt, the Pin it's associated with that we're using and enable the Pull-Up
+  // Many Arduino Cores now support the digitalPinToInterrupt() function that makes it easier to figure out the
+  // Interrupt Number for the Arduino Pin number, which reduces confusion. 
+#ifdef digitalPinToInterrupt
+  Dcc.pin(DCC_PIN, 0);
+#else
+  Dcc.pin(0, DCC_PIN, 1);
+#endif
   
   // Call the main DCC Init function to enable the DCC Receiver
   Dcc.init( MAN_ID_DIY, 10, CV29_ACCESSORY_DECODER | CV29_OUTPUT_ADDRESS_MODE, 0 );