(NDK) Added Listener component and system

Former-commit-id: 0553c4ad9a7e33608e9ab91bd4ca8812272a6293

SDK/src/NDK/Components/ListenerComponent.cpp

@@ -0,0 +1,10 @@
+// Copyright (C) 2015 Jérôme Leclercq
+// This file is part of the "Nazara Development Kit"
+// For conditions of distribution and use, see copyright notice in Prerequesites.hpp
+
+#include <NDK/Components/ListenerComponent.hpp>
+
+namespace Ndk
+{
+	ComponentIndex ListenerComponent::componentIndex;
+}

SDK/src/NDK/Components/NodeComponent.cpp

@@ -6,5 +6,5 @@
 
 namespace Ndk
 {
-	ComponentIndex NodeComponent::componentIndex = 0;
+	ComponentIndex NodeComponent::componentIndex;
 }