Do not clear constraintsAndComplements_ after graph initialization,
  Add method clearConstraintsAndComplement(),
  call this method in ProblemSolver::initConstraintGraph().

This reverts commit 0d81bac3.

  - GraphComponent::numericalConstraints is virtual,
  - reimplemented in Edge a follows:
    - if edge is not initialized, call parent implementation,
    - otherwise return constraints that are in the solver.
  - The differences are that:
    1. constraints and complements are replaced by explicit constraints,
    2. constraints of the containing node are also returned.

  - when inserting them. Throw if they are.
  - Add a test.

  to comply with modification in hpp-constraints.

  RelativeTransformation -> RelativeTransformationSE3 with mask.

  - methods formerly taking a const reference to Problem as input now take
    a shared pointer to const Problem.

  Set error threshold for each internal edge to the value of the edge divided
  by the number of internal edges.

  -> 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.