anchor.diff:    "Behaviour to run away from `PLAYER'."
     (or
      (when player
  -     (let ((pos (entity-position boid))
  -           (player-pos (entity-position player)))
  +     (let* ((pos (entity-position boid))
  +            (player-pos (entity-position player))
  +            (distance (p2dm:distance-between-vectors pos player-pos))
  +            (lr (linear-repulsion (boid-perception-range boid) distance)))
          (static-priority (ddv pos
  -                             (p2dm:subtract-vectors pos player-pos)
  +                             (p2dm:scaled-vector (p2dm:subtract-vectors pos player-pos)
  +                                                 lr)
                                :avoid-player)
  -                        1.0)))
  +                        lr)))
      (p2dm:make-vector-2d)))
   
   
positive.code: 
  (defparameter +max-boid-steering+ 60.0)
  (defparameter +max-boid-speed+ 60.0)
  (defparameter +min-boid-separation+ 20)
  
  (defparameter +min-boid-distance-to-game-area-boundary+ 30)
  
  
negative.code:                               (p2dm:scaled-vector (reduce #'p2dm:add-vectors boids :key #'entity-velocity)
                                                    (/ 1.0 boids-cnt))
                                :alignment)
                           0.3)
          (p2dm:make-vector-2d))))
  
  (defun separate (boid all-boids)
  