preparing serialization of entities

Game/Entity/Entity.cpp

@@ -1,3 +1,25 @@
 #include <Entity/Entity.h>
 
+#include <Core/Common/serialization.h>
+
 DEFINE_ENTITY(Inert);
+
+void serialize(archive& ar, NonNullPtr<Entity> entity)
+{
+    serialize_elem(ar, entity->ID);
+
+    if (ar.loading)
+    {
+        serialize_elem(ar, entity->Kind->kind);
+    }
+    else
+    {
+        uint8 kind;
+        serialize_elem(ar, kind);
+        entity->Kind = kEntity_type_class_ptr[kind];
+    }
+
+    serialize_elem(ar, entity->X);
+    serialize_elem(ar, entity->Y);
+    serialize_elem(ar, entity->Z);
+}