Adds new optional --replace-nans mean and --replace-nans zero CLI options to the gridsearch, which respectively replace nan values in the function contour by the function mean, or by zero.
Default behaviour is to do no replacement, and instead throw an exception.
--replace-nans meanand--replace-nans zeroCLI options to the gridsearch, which respectively replace nan values in the function contour by the function mean, or by zero.Fixes #316