Make actor flee from a combat when cannot reach a target (#5851)

The idea is to avoid pathfinding fallback. Instead of making actors try to go straight to a target ignoring possible obstacles and cliffs as it was in 0.46 make them flee. Actors that are able to do a ranged combat should not flee. For the case described in the bug this works but I can imagine there is a lot of other cases where current change is wrong so this need some testing.