[Feature Request] Add variation to the responding POTA station

[bugbbq]

For the POTA activator, would it be possible to be able to customize the response using variables? It would be nice to be able to have some variation in order to make the POTA activation even more realistic.

An example of variable use could be something like this in a input field under the Responding Stations Setting:

"RR UR 5{5,7,N}N 5{5,7,N}N {#State} {#State} BK"

Mind you, I'm not a developer and my use of variables are clunky and not exact, so please excuse my terrible job at it!

Thanks!

[johnsonm]

I've added variations on responses in my field day implementation, for field day, but it could easily be extended to other modes. See #71 for what I've done there.