Closes #416: Fix Gridded Factories
Convert y-values to arrays (if not already), then interpolate each y-value in the array with respect to x. If y-values were originally arrays, return an array, otherwise return just the first value in the array.
Convert y-values to arrays (if not already), then interpolate each y-value in the array with respect to x. If y-values were originally arrays, return an array, otherwise return just the first value in the array.