refactor renames for clarity

examples/src/UdpMulticastExamples/MulticastReceiver.java

 package UdpMulticastExamples;
 
-import edu.nps.moves.dis7.utilities.DisThreadedNetIF;
+import edu.nps.moves.dis7.utilities.DisThreadedNetworkInterface;
 import java.io.*;
 import java.net.*;
 import java.nio.ByteBuffer;
@@ -53,7 +53,7 @@ public class MulticastReceiver {
             group = new InetSocketAddress(multicastAddress, DESTINATION_PORT);
             
             // Join group useful on receiving side
-            multicastSocket.joinGroup(group, ni = DisThreadedNetIF.findIpv4Interface());
+            multicastSocket.joinGroup(group, ni = DisThreadedNetworkInterface.findIpv4Interface());
             // You can join multiple groups here
             
             System.out.println("Multicast address/port: " + multicastAddress.getHostAddress() + "/" + DESTINATION_PORT);

examples/src/UdpMulticastExamples/MulticastSender.java

 package UdpMulticastExamples;
 
-import edu.nps.moves.dis7.utilities.DisThreadedNetIF;
+import edu.nps.moves.dis7.utilities.DisThreadedNetworkInterface;
 import java.io.*;
 import java.net.*;
 import java.util.logging.Level;
@@ -62,7 +62,7 @@ public class MulticastSender {
             
             group = new InetSocketAddress(multicastAddress, DESTINATION_PORT);
             // Join group useful on receiving side
-            multicastSocket.joinGroup(group, ni = DisThreadedNetIF.findIpv4Interface());
+            multicastSocket.joinGroup(group, ni = DisThreadedNetworkInterface.findIpv4Interface());
             // You can join multiple groups here
             
             byte[] buffer = baos.toByteArray();