added solutionswitch in exams2qti21

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/exams@645 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
insert ititle as item title in exams2qti21() now

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/exams@646 edb9625f-4e0d-4859-8d74-9fd3b1da38cb