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.

  - copied code from Wildmagic (http://www.geometrictools.com) nodified
    boost license.
  - collision detection calls distance function.

  - use API distance function instead of selecting gjk solver.

abs() only works for integers,
replace with std::abs() for floaing point

Update another tests (GJK): sphere-sphere, box-box, sphere-box, cylinder-cylinder, cone-cone, cone-cylinder

Update another tests: box-box, sphere-box, sphere-capsule, cylinder-cylinder, cone-cone, cone-cylinder