Return references instead of pointers from the config system.

We used to return NULL from these methods but now we return an empty
block so this can never actually be null now.

modules/global/gl_queue.cpp

@@ -69,7 +69,7 @@ private:
 			return;
 		}
 
-		auto maxqueue = Config->GetModule(this->module)->Get<size_t>("maxqueue", "10");
+		auto maxqueue = Config->GetModule(this->module).Get<size_t>("maxqueue", "10");
 		if (global->CountQueue(source.nc) >= maxqueue)
 		{
 			source.Reply(_("You can not queue any more messages."));