Added WifiServer::begin(uint16_t port) method, listening port can be changed at runtime (#4123)

Author: LuchoBecerra

libraries/ESP8266WiFi/src/WiFiServer.cpp

@@ -56,7 +56,12 @@ WiFiServer::WiFiServer(uint16_t port)
 }
 
 void WiFiServer::begin() {
+	begin(_port);
+}
+
+void WiFiServer::begin(uint16_t port) {
     close();
+	_port = port;
     err_t err;
     tcp_pcb* pcb = tcp_new();
     if (!pcb)

libraries/ESP8266WiFi/src/WiFiServer.h

@@ -51,6 +51,7 @@ class WiFiServer : public Server {
   WiFiClient available(uint8_t* status = NULL);
   bool hasClient();
   void begin();
+  void begin(uint16_t port);
   void setNoDelay(bool nodelay);
   bool getNoDelay();
   virtual size_t write(uint8_t);