Flexible: add  volume mapping

git-svn-id: svn://scm.gforge.inria.fr/svnroot/sofa/trunk@9981 b7f1a160-662a-0410-a6d8-bea165342f16
(Partial)FixedConstraint: partial fix to take into account "fixAll" parameter


git-svn-id: svn://scm.gforge.inria.fr/svnroot/sofa/trunk@9982 b7f1a160-662a-0410-a6d8-bea165342f16