Added packet type constants and other stylistic changes

PubSubClient/PubSubClient.h

@@ -12,6 +12,23 @@
 #define MAX_PACKET_SIZE 128
 #define KEEPALIVE 15000 // max value = 255000
 
+// from mqtt-v3r1 
+#define MQTTPROTOCOLVERSION 3
+#define MQTTCONNECT     1 << 4  // Client request to connect to Server
+#define MQTTCONNACK     2 << 4  // Connect Acknowledgment
+#define MQTTPUBLISH     3 << 4  // Publish message
+#define MQTTPUBACK      4 << 4  // Publish Acknowledgment
+#define MQTTPUBREC      5 << 4  // Publish Received (assured delivery part 1)
+#define MQTTPUBREL      6 << 4  // Publish Release (assured delivery part 2)
+#define MQTTPUBCOMP     7 << 4  // Publish Complete (assured delivery part 3)
+#define MQTTSUBSCRIBE   8 << 4  // Client Subscribe request
+#define MQTTSUBACK      9 << 4  // Subscribe Acknowledgment
+#define MQTTUNSUBSCRIBE 10 << 4 // Client Unsubscribe request
+#define MQTTUNSUBACK    11 << 4 // Unsubscribe Acknowledgment
+#define MQTTPINGREQ     12 << 4 // PING Request
+#define MQTTPINGRESP    13 << 4 // PING Response
+#define MQTTDISCONNECT  14 << 4 // Client is Disconnecting
+#define MQTTReserved    15 << 4 // Reserved
 
 class PubSubClient {
 private: