CMAKE: group projects into folders when generation visual studio solutions

git-svn-id: svn://scm.gforge.inria.fr/svnroot/sofa/trunk@9457 b7f1a160-662a-0410-a6d8-bea165342f16
FIX: LineModel::topology was always NULL

git-svn-id: svn://scm.gforge.inria.fr/svnroot/sofa/trunk@9458 b7f1a160-662a-0410-a6d8-bea165342f16