animals / fauna flee in straight lines

[dialectric]

In the Sept. 5 build, when chased by a non-range-attack unit, animals will run in a straight line to the edge of the map or an obstruction, then turn and continue to run in a straight line in a new direction. This is unrealistic, and the animal's escape path should be randomized.

To recreate, attack an animal that flees with any unit without a range attack. the two will run around the map, showing the path on the mini-map. the paths are always straight horizontal or vertical lines.

[Freagarach]

Refs. #3919.