Add randomness to the choices the AI makes

The AI will now not always choose the optimal node to get away from the
player, occasionally choosing the second or, more rarely, the thirdmost
distant node. It will never move next to the player unless absolutely
necessary, and will never move directly onto the player.
Set the maximum zoom to 11

At 11 the entire vertical scope of the map is visible, so it should be
the maximum zoom.