-registering same system multiple times only replace pointer for callback

-added export attributes (required by windows to make DLL library, not work at now due to DMD bugs)
-interface D files to import

import/ecs/id_manager.di

@@ -0,0 +1,20 @@
+// D import file generated from 'source\ecs\id_manager.d'
+module ecs.id_manager;
+import ecs.entity;
+import ecs.vector;
+struct IDManager
+{
+	EntityID getNewID();
+	void releaseID(EntityID id);
+	void update(ref Entity entity);
+	Entity* getEntityPointer(EntityID id);
+	bool isExist(EntityID id);
+	struct Data
+	{
+		uint counter = 0;
+		uint next_id = (uint).max;
+		Entity* entity = null;
+	}
+	private uint m_next_id = 0;
+	Vector!Data m_ids_array;
+}