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variable: $fadef -- ipsilateral fade out
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default: 0.7

The "fad:" entry controls the fraction of the
colorscale that is *not* grayed-out (or
yellowed-out if ipsiyellowfact>0.0).

Changing $fadef has no effect if $angle_cycles is
set to an integer (1, 2, ...)

With $fadef set to 0.99, ipsilateral graying-out
is disabled.  Lower fadef's result in a larger
percentage of phases being grayed-out.  At
fadef=0.0, 2/3 of the color wheel is grayed out.
