Flexible: added test suite. For now, only testing the corotational strain mapping. Principal stretches is hard to test, because principal stretches are not sorted and so a vector comparison is not enough.

git-svn-id: svn://scm.gforge.inria.fr/svnroot/sofa/trunk@9546 b7f1a160-662a-0410-a6d8-bea165342f16
small fixes in Compliant doc

git-svn-id: svn://scm.gforge.inria.fr/svnroot/sofa/trunk@9547 b7f1a160-662a-0410-a6d8-bea165342f16