from BVHCollisionTraversalNode::leafTesting to
  GJKSolver_indep::shapeDistance<TriangleP, TriangleP>.

  - do not run EPA algorithm to compute penetration depth and normal.

  - Collision detection calls distance computation and returns collision
    if the distance between objects is below the security margin.
  - This modification requires a modification in the structure of the software
    to make collision detection and distance computation closer.
  - GJKSolver_indep::shapeTriangleDistance and
    GJKSolver_indep::shapeTriangleIntersect have been replaced by
    GJKSolver_indep::shapeTriangleInteraction.

  - this member stores the normal (direction object 2 should be translated by
    the penetration depth to make objects collision free) in case boths objects
    are in collision.

  instead of -1.

  when checking sizes of vectors.

  - remove unused variable.

  - use GJK algorithm to detect collision between triangles.
  - Remove methods
    - MeshCollisionTraversalNodeOBB::leafTesting,
    - MeshCollisionTraversalNodeRSS::leafTesting,
    - MeshCollisionTraversalNodekIOS::leafTesting,
    - MeshCollisionTraversalNodeOBBRSS::leafTesting,
    use parent class implementation instead.

  - old constructor is deprecated.

  - store const CollisionRequest& as a member instead of CollisionRequest,
  - remove member CollisionRequest::enable_distance_lower_bound,
  - modify constructors of all derived classes.

  - overlap method without sqrDistLowerBound as an argument call the method
    with sqrDistLowerBound as an argument.

  Simplex::c -> Simplex::vertex.
  Simplex::p -> Simplex::coefficient.

  - security_margin is the distance below which collision test returns
    collision,
  - break_distance is the distance below which bounding boxes are broken
    down.