Fix misnamed clients in logging plugin logging.

logging/src/com/dmdirc/addons/logging/LoggingManager.java

         if (channelClient == null) {
             return overrideNick.isEmpty() ? "Unknown Client" : overrideNick;
         } else if (overrideNick.isEmpty()) {
-            return channelmodeprefix ? channelClient.toString() : channelClient.getNickname();
+            return channelmodeprefix ? channelClient.getModePrefixedNickname()
+                    : channelClient.getNickname();
         } else {
             return channelmodeprefix ? channelClient.getImportantMode() + overrideNick :
                     overrideNick;