These meter scales should adapt to the rigCaps data about meter
calibrations.

Non-adapting meters:
EMF/dBu/dBm from the R-8600
Audio Meters, which are not really from a radio per-se anyway
Center meter, as this seems to only be the R-8600 and it got messy
immediately.

There's considerable code in here which attempts to present a reasonable
number of tic marks and values. This is needed because some radios
provide a much wider span of values than others. For example, Icom
meters up to 20:1 SWR, whereas Kenwood seems to go up to 5:1.

We should probably consider an option to trim these super-wide span
meters for more reasonable ranges (who needs to see SWR past 5:1???) as
I think most people would favor more visual precision.