objects of class "SymmetryProblem" didn't check validity

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/coin@838 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
'ft' gained argument 'class' to allow for "SymmetryProblem"

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/coin@839 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
tweak

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/coin@840 edb9625f-4e0d-4859-8d74-9fd3b1da38cb