- The frame in which closest points were expressed was neither clear, nor
    consistent.

This reverts commit 9122b15d.

  Distance computation between boxes does not seem to be very accurate.

  This enables users to install the official version of fcl together with
  hpp-fcl.

  Avoid conflict between fcl official version as installed by ROS and hpp
  modified version.

  - returning a small value for the distance lower bound makes time of
    computation of continuous collision checking very high. It is better to
    break the bounding volumes to get a better bound, eventhough it increases
    the time of computation.

  - throw exception if called.

  - in class CollisionTraversalNodeBase and derived classes.

  sqrt should be applied after method call.

  enable_distance_lower_bound.

  - add a Boolean value in CollisionRequest to trigger this option,
  - if selected, fcl::collision function will compute a lower bound
    on the distance between the two objects if they do not collide.