-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/entity.di

@@ -0,0 +1,30 @@
+// D import file generated from 'source\ecs\entity.d'
+module ecs.entity;
+import ecs.manager;
+struct EntityID
+{
+	uint id;
+	uint counter;
+}
+struct Entity
+{
+	EntityID id;
+	void updateID();
+	T* getComponent(T)()
+	{
+		EntityManager.EntitiesBlock* block = gEM.getMetaData(&this);
+		EntityManager.EntityInfo* info = block.type_data;
+		if (T.component_id >= info.deltas.length || info.deltas[T.component_id] == 0)
+			return null;
+		return cast(T*)(cast(void*)&this + info.deltas[T.component_id]);
+	}
+}
+export struct EntityTemplate
+{
+	ubyte[] entity_data;
+	EntityManager.EntityInfo* info;
+	T* getComponent(T)()
+	{
+		return cast(T*)(entity_data.ptr + info.deltas[T.component_id]);
+	}
+}