[Feature Request] Add support for whispers

[KoboldCatgirl]

Hi there! I recognize that I don't really know a lot about coding, and I wouldn't be surprised if this was too difficult to pull off, but I know Polyglot was able to get supported, so I'm hoping there's a chance.

My group uses whispers (with the /w function) a lot to allow for character secrets. Often these whispers get posted to the theater by accident (always mortifying), and even when this mistake isn't made, it's sort of a shame that we can't enjoy using the theater when we want to do private conversations.

It would be very nice if the theater could either ignore whispered messages entirely, but better still if the theater could selectively display whispered messages only to the recipients.