(NDK) Added explicit initialisation

Components and systems just can't be initialized at startup, so we need
some kind of explicit initialisation. I followed the same layout as the
others modules by adding a core class (Ndk::Sdk) which will initialize
components and systems, and Nazara's modules.

This is starting to get serious, I like it.


Former-commit-id: 263500e8d16db70ef7f92047b8a7e3235c08bcd0

SDK/include/NDK/BaseComponent.hpp

@@ -16,6 +16,8 @@ namespace Ndk
 {
 	class NDK_API BaseComponent
 	{
+		friend class Sdk;
+
 		public:
 			using Factory = std::function<BaseComponent*()>;
 
@@ -32,6 +34,9 @@ namespace Ndk
 			static ComponentIndex RegisterComponent(ComponentId id, Factory factoryFunc);
 
 		private:
+			static bool Initialize();
+			static void Uninitialize();
+
 			struct ComponentEntry
 			{
 				ComponentId id;