- 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

Conflicts:
	test/test_fcl_geometric_shapes.cpp

Fix incorrect state check in BVHModel::addVertex(~)

Conflicts:
	test/test_fcl_utility.cpp
	test/test_fcl_utility.h

Support Halfspace through main [collision/distance/continuous collision] interface