make random stack sizes optional

in my last pull request i changed the defaul behaviour of aux to max stack sizes to random stack sizes.
this pull reqeust chagnes this back and adds the /aux post stack command to toggle stacks off and get random post sizes instead

aux-addon.lua

@@ -59,6 +59,7 @@ function handle.LOAD()
         crafting_cost = true,
         post_bid = false,
         post_duration = post.DURATION_24,
+		post_stack = true,
         items = {},
         item_ids = {},
         auctionable_items = {},