Add cost in GraphComponent.

[steeringMethod::Graph] If q1 == q2, call problem inner steering method.

Improve graph validation + fix dynamic cast issue.

  value for solvers.

  - 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.

  - check that a triple of constraint is not registered twice.

* The implementation has never been completed.