ImagePlugin: add toolbox

git-svn-id: svn://scm.gforge.inria.fr/svnroot/sofa/trunk@9809 b7f1a160-662a-0410-a6d8-bea165342f16
ImagePlugin: add mechanism to put widget in ToolBar

git-svn-id: svn://scm.gforge.inria.fr/svnroot/sofa/trunk@9810 b7f1a160-662a-0410-a6d8-bea165342f16