Minor QoL improvement to ToT rewards

[srmalloy]

It's a really niggly thing, and won't change much of anything if it's not done, but the way that receiving a "TREAT" works now is that the server decides what you're getting, and if it's a ToT costume, randomly picks a ToT costume temp power from the available list; if you already have that temporary power, you just get the "TREAT" announcement, without any actual reward. Would it be easy to, if the server picked a costume your character already had, to generate a random piece of Halloween salvage instead, so that you don't get "treats" with no reward?