Vario audio tone

[caiuspetronius]

I wonder if one could add the vario tone as an alternative to the voice readouts along the lines of https://hackaday.io/project/175220-flysky-variometer? EdgeTx can't run any Special Functions scripts while iNav.lua is running (for some reason). I used GPS altitude to calculate vertical speed for the variometer (with the FrSky telemtery the vertical speed is calculated by default) and it worked surprisingly well, so it would be a very useful feature.