-> generateTargetConfigOnLeaf.

  - reference ICRA 2017 paper.

  Make previous methods deprecated
  Rename Graph::configConstraint(EdgePtr_t) into targetConstraint.

  make old methods deprecated.
  This will homogeneize with hpp-manipulation-corba naming.

  - Implement method GraphPathValidation::setSecurityMargins.
  - Add method Edge::securityMarginForPair to set a security margin for
    a pair of joints along an edge.

  from is a python keyword. This is an issue when using python bindings.

  - create one solver by waypoint,
  - detect for each parameterizable constraint and each waypoint if
    - the right hand side is equal to the right hand side for initial config,
    - the right hand side is equal to the right hand side for goal config,
    - the right hand side is equal to the right hand side for previous waypoint.
  - iteratively solve waypoints after initializing right hand sides.

* The implementation has never been completed.

* make steeringMethod setter accessible.