Newcomb's paradox (partial) bug fix and new scenario

[MichaelJFishman]

The existing Newcomb's paradox tutorial sorts decisions by decision name when finding the best decision, rather than sorting by the value of the decision. This fixes that. However, the AI still always recommends choosing both boxes.

This also adds a new scenario to the Newcomb's paradox notebook.

The setup:

The player can choose one of two boxes, a blue or a green one. The player always chooses the box that matches their favorite color, and the adversarial AI always puts the prize in the box that is NOT the player's favorite color. The friendly AI therefore always recommends that the player choose the box that is NOT their favorite color.