possibility to extend the // doftable on some ghost element (which touch the interprocess faces)
add parameters in functionspace to take into account the extended doftable
add boost parameter
 accept extended stencil with ghost elt
fix projector : Pattern::EXTENDED is uselessgit diff projector.hpp and also the default backend ( Backend<double>::build( BACKEND_PETSC ) is obselete I think )
reactivate integrate on interprocess faces
use Pdh instead of Odh and use extended dof table in //