New post "why-signals-bend" with ten hand-rolled canvas scenes
(LOS, Earth curvature, Fresnel, knife-edge and rounded diffraction,
refractivity profile, ray tracing, duct trapping, duct types,
and the real 65 km QTH-to-W5HN/B path with 4/3-Earth bulge).
Also drop QSO/em-dash conventions from prop1 and the
"written by humans" footer line.
