Making Radio "Supplementary channel" codes permanent.

[Paineframe]

Secchat in particular has no reason to be easy for newcomers, because newcomers shouldn't be playing sec. Honestly, I feel it should default to the "Unwanted" column the same way all traitor roles default to disabled.

There's also an especially large cost to changing the meaning of :s, because AIs and borgs have more reason to use their chat and more need to keep their chat secret than sec does. Not everyone reads the changelogs or the start-of-round popup text, and borgs don't have headsets to examine, so changing the silicon channel will inevitably lead to a lot of law violations.