Allow the user to minimize or maximize the score

It is much easier for a user to define if their score needs to be minimized (I want no waste) or maximized (I want high strength). It is not easy for a user to remember to turn a score into a negative number, for the sake of feeding it to the back-end where the algorithm always seeks to minimize the score.

It would be preferable if the user simply chose whether the score is to be minimized or maximized via some flag in the UI, and then "flip" the values behind the scenes when maximizing.

As an added bonus, this behaviour should also carry over to all plots :)