Add destructor for memory cleanup

Author: sebromero

libraries/WiFi/src/WiFiUdp.cpp

@@ -13,6 +13,10 @@ arduino::WiFiUDP::WiFiUDP() {
     // if this allocation fails then ::begin will fail
 }
 
+arduino::WiFiUDP::~WiFiUDP() {
+    delete[] _packet_buffer;
+}
+
 uint8_t arduino::WiFiUDP::begin(uint16_t port) {
     // success = 1, fail = 0
 
@@ -36,8 +40,7 @@ uint8_t arduino::WiFiUDP::begin(uint16_t port) {
 }
 
 void arduino::WiFiUDP::stop() {
-    _socket.close();
-    delete[] _packet_buffer;
+    _socket.close();    
 }
 
 int arduino::WiFiUDP::beginPacket(IPAddress ip, uint16_t port) {

libraries/WiFi/src/WiFiUdp.h

@@ -45,6 +45,7 @@ class WiFiUDP : public UDP {
 
 public:
   WiFiUDP();  // Constructor
+  ~WiFiUDP();
   virtual uint8_t begin(uint16_t);	// initialize, start listening on specified port. Returns 1 if successful, 0 if there are no sockets available to use
   // virtual uint8_t beginMulticast(IPAddress, uint16_t);  // initialize, start listening on specified multicast IP address and port. Returns 1 if successful, 0 if there are no sockets available to use
   virtual void stop();  // Finish with the UDP socket