[developers] Re: Updating TD-H3 for more recent variants

I'll look at how you've implemented other guards and try to sing from the same songsheet.

There's a lot of prior art, but not all of which I'd recommend. With a 15+ year code base, there are lots of things we've done/tried that I wouldn't recommend. Let's figure out how we're going to tell them apart and then we can figure out the best plan.

Also, if the radio doesn't balk at them being in the radio as TX-able even if the older firmwares refuse, that might just be the best plan. CHIRP won't tell the user they're putting in a channel they won't be able to transmit on, but not all the drivers can/do provide that feedback. This driver does, mostly because of the three (four now?) variants.

--Dan