Avoidance example adjustments

- Updated UnitySteer reference.
- Increased estimation time. Since the agents don't get upated ever frame
  it's best to look ahead. Since SteerForSphericalObstacles no longer
  considers every collision the same, this means we can freely look at
  more objects.
- Reduced turn time. It makes no sense to have a turn time that is higher
  than our obstacle collision estimation time.