If any fingering does not include a target frequency, do not include it in error calculation;
do not apply any penalty value.
Reverse target and predicted when calculating cents difference,
so that the sign of the error agrees with the difference displayed in the "Calculate Tuning" table.
Change FmaxEvaluator and FminEvaluator to use cent differences, rather than raw impedance or gain values.
Cent differences give a more level playing field between different notes.
Move "underconstrained" warning to optimizer.  Display elapsed time of optimization.