Repair bug noted by Paul Caskey: neqsel() has been generating a bogus

result, in fact nearly the opposite of what it should, because it
was passing the not-equal operator to eqsel() which would use it to
compare the value against the most common value in the column, and
of course obtain the wrong result therefrom.  Must pass the equality
operator to eqsel() instead.  Fortunately that's easy to get from
the oprnegate link.