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.cpp

@@ -0,0 +1,32 @@
+/* Copyright: (c) Kayne Ruse 2014
+ * 
+ * This software is provided 'as-is', without any express or implied
+ * warranty. In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ * 
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ * 
+ * 1. The origin of this software must not be misrepresented; you must not
+ * claim that you wrote the original software. If you use this software
+ * in a product, an acknowledgment in the product documentation would be
+ * appreciated but is not required.
+ * 
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ * misrepresented as being the original software.
+ * 
+ * 3. This notice may not be removed or altered from any source
+ * distribution.
+*/
+#include "client_data.hpp"
+
+int ClientData::IncrementAttempts() {
+	lastBeat = Clock::now();
+	return attemptedBeats++;
+}
+
+int ClientData::ResetAttempts() {
+	lastBeat = Clock::now();
+	return attemptedBeats = 0;
+}