Adding parameter to track distance lower bound between BVH (preliminary).

include/fcl/BV/AABB.h

include/fcl/BV/BV_node.h

include/fcl/BV/OBB.h

include/fcl/BV/OBBRSS.h

include/fcl/BV/RSS.h

include/fcl/BV/kDOP.h

include/fcl/BV/kIOS.h

include/fcl/collision_data.h

include/fcl/collision_node.h

include/fcl/traversal/traversal_node_base.h

include/fcl/traversal/traversal_node_bvh_shape.h

include/fcl/traversal/traversal_node_bvhs.h

include/fcl/traversal/traversal_node_shapes.h

include/fcl/traversal/traversal_recurse.h

src/BV/OBB.cpp

src/BV/OBBRSS.cpp

src/BV/kIOS.cpp

src/collision_func_matrix.cpp

src/collision_node.cpp

src/continuous_collision.cpp