Replace SLAM internal 6 DoF state vector by an homogeneous matrix.
@gabriel.devillers @melanie.carriere
Replace SLAM internal 6 DoF state vector by an homogeneous matrix (stored as Eigen::Isometry3d).
Even if it has more parameters (4 x 4 matrix) instead of 6 scalars, it leads to much more cleaner code, a little faster as no conversions to homogeneous matrix are needed for transformations, and much more stable as no euler angles are used, avoiding conventions/representations/singularities.