Added decending npc to slaves. Custom feature.. nothing much.

git-svn-id: https://svn.code.sf.net/p/rathena/svn/trunk@6849 54d463be-8e91-2dee-dedb-b68131a5f0ec

src/map/mob.c

@@ -1512,6 +1512,7 @@ int mob_convertslave_sub(struct block_list *bl,va_list ap)
 		md->master_id = md2->master_id;
 		md->state.killer = md2->state.killer;
 		md->special_state.ai = md2->special_state.ai;
+		md->nd = md2->nd;
 	}
 
 	return 0;