Add an inline toEigen function for matrix3_t
Update to new version of fcl

  - move fcl forward declarations to fcl,
  - create doxygen link to fcl documentation.
Express parameters in fcl::CollisionRequest constructor.
Cosmetic: fix documentation of JointConfiguration::distance.
Keep track of collisions and distance body pairs.
Make methods Joint::computePosition and Joint::recursiveComputePosition const.

  - make internal compuation members mutable.
ObjectVector_t is now a list of CollisionObjectPtr_t.
Keep track of obstacles in class Device.
Cosmetic change.
Add forward declarations for anchor joint.
When creating a collision object, set positionInJointFrame_ to global position.
Add a function to write a configuration in a string.
Add parameter in Gripper
Comment function SO3JointConfig::integrate