Add initial ECS support

src/Nazara/Core/ECS.cpp

@@ -0,0 +1,11 @@
+// Copyright (C) 2020 Jérôme Leclercq
+// This file is part of the "Nazara Engine - Core module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#include <Nazara/Core/ECS.hpp>
+#include <Nazara/Core/Debug.hpp>
+
+namespace Nz
+{
+	NAZARA_CORE_API ECS* ECS::s_instance = nullptr;
+}