The multi-frame waveform header (USB path) read the second frequency field
as an absolute high edge, but in center mode it is a span — so high < low and
the panadapter had no valid range to map the trace onto (blank scope). It now
applies the same center+span vs low+high disambiguation the IC-7610 single-
frame path already used. FIXED mode was unaffected.
Also stamps changelog 0.20.10 with today's date.