Snapshot problem

[LouisLafontaine]

Currently after the new acceleration vector of a boid (i) has been computed, that boid is updated and put back in the list of all boids. So the (i+1) boid's acceleration is based on the already updated (0 to i) boid's accelerations.

The goal here is to update the acceleration vector of every boid so that the acceleration of the aforementioned (i+1) boid would be calculated based on the non updated (0 to i) boid's acceleration.