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.

   This fixes test_fcl_simple.

  - 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.

Fix warning about abs() with float's

Fix box-box intersection algorithm with test

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

Conflicts:
	test/test_fcl_geometric_shapes.cpp

Fix inconsistent normal directions