Add wider IPAddress support in api

PubSubClient/examples/mqtt_basic/mqtt_basic.ino

@@ -1,6 +1,6 @@
 /*
- Basic MQTT example 
- 
+ Basic MQTT example
+
   - connects to an MQTT server
   - publishes "hello world" to the topic "outTopic"
   - subscribes to the topic "inTopic"
@@ -12,8 +12,8 @@
 
 // Update these with values suitable for your network.
 byte mac[]    = {  0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED };
-byte server[] = { 172, 16, 0, 2 };
-byte ip[]     = { 172, 16, 0, 100 };
+IPAddress ip(172, 16, 0, 100);
+IPAddress server(172, 16, 0, 2);
 
 void callback(char* topic, byte* payload, unsigned int length) {
   // handle message arrived
@@ -35,4 +35,3 @@ void loop()
 {
   client.loop();
 }
-