UDPNetworkUtility accepts addresses by value, encapsulated ClientData

I started encapsulating ClientData, and I added the internals for the
heartbeat ssytem. However, when I took a look inside UDPNetworkUtility, I
realized that I didn't have to pass the IPaddresses by reference anymore.
Therefore, I've changed it to accept the addresses by value, and I'm
committing that change right away before I finish the heartbeat system.

This engine is really shaping up, I think.

server/client_data.hpp

@@ -24,9 +24,31 @@
 
 #include "SDL/SDL_net.h"
 
-struct ClientData {
+#include <chrono>
+
+//TODO: ClientManager?
+class ClientData {
+public:
+	typedef std::chrono::steady_clock Clock;
+
+	ClientData() = default;
+	ClientData(IPaddress add): address(add) {}
+	~ClientData() = default;
+
+	IPaddress SetAddress(IPaddress add) { return address = add; }
+	IPaddress GetAddress() { return address; }
+
+	Clock::time_point GetLastBeat() { return lastBeat; }
+
+	int GetAttempts() { return attemptedBeats; }
+	int IncrementAttempts();
+	int ResetAttempts();
+
+private:
 	IPaddress address = {0,0};
-	//TODO: ping system?
+
+	Clock::time_point lastBeat = Clock::now();
+	int attemptedBeats = 0;
 };
 
 #endif