Added homeSpan.setPairCallback() method

Callback function must be of type void()(boolean isPaired).  Will be called when device is paired and when device is unpaired.  Allows for user-defineable actions upon device pairing/unpairing.

src/HAP.cpp

@@ -661,6 +661,9 @@ int HAPClient::postPairSetupURL(){
       LOG1("\n*** ACCESSORY PAIRED! ***\n");
       homeSpan.statusLED.on();
       
+      if(homeSpan.pairCallback)                     // if set, invoke user-defined Pairing Callback to indicate device has been paired
+        homeSpan.pairCallback(true);
+      
       return(1);        
              
     break;
@@ -1592,6 +1595,8 @@ void HAPClient::removeController(uint8_t *id){
       LOG1("That was last Admin Controller!  Removing any remaining Regular Controllers and unpairing Accessory\n");  
       mdns_service_txt_item_set("_hap","_tcp","sf","1");           // set Status Flag = 1 (Table 6-8)
       homeSpan.statusLED.start(LED_PAIRING_NEEDED);
+      if(homeSpan.pairCallback)                                    // if set, invoke user-defined Pairing Callback to indicate device has been paired
+        homeSpan.pairCallback(false);
     }
 
     LOG2("\n");

src/HomeSpan.h

@@ -131,6 +131,7 @@ struct Span{
   char otaPwd[33];                                            // MD5 Hash of OTA password, represented as a string of hexidecimal characters
   boolean otaAuth;                                            // OTA requires password when set to true
   void (*wifiCallback)()=NULL;                                // optional callback function to invoke once WiFi connectivity is established
+  void (*pairCallback)(boolean isPaired)=NULL;                // optional callback function to invoke when pairing is established (true) or lost (false)
   boolean autoStartAPEnabled=false;                           // enables auto start-up of Access Point when WiFi Credentials not found
   void (*apFunction)()=NULL;                                  // optional function to invoke when starting Access Point
   
@@ -191,6 +192,7 @@ struct Span{
   void setSketchVersion(const char *sVer){sketchVersion=sVer;}            // set optional sketch version number
   const char *getSketchVersion(){return sketchVersion;}                   // get sketch version number
   void setWifiCallback(void (*f)()){wifiCallback=f;}                      // sets an optional user-defined function to call once WiFi connectivity is established
+  void setPairCallback(void (*f)(boolean isPaired)){pairCallback=f;}      // sets an optional user-defined function to call when Pairing is established (true) or lost (false)
   void setApFunction(void (*f)()){apFunction=f;}                          // sets an optional user-defined function to call when activating the WiFi Access Point
   void protectPinISR(uint8_t pin){ProtectedGPIOs[pin]=0;}                 // protects ISR on pin from NVS operations
   

src/src.ino

@@ -50,7 +50,6 @@ void setup() {
       new Characteristic::On(0);
       new Characteristic::LightMode("HELLO");
       new Characteristic::DarkMode();
-      new Characteristic::DarkMode("OVERRIDE");
       new Characteristic::Brightness(50);
       new Characteristic::Name("Light 1");
       new Characteristic::ColorTemperature();