exposed additional functions

git-svn-id: http://openmesh.org/svnrepo/OpenMesh@1088 fdac6126-5c0c-442c-9429-916003d36597
added three unit tests

git-svn-id: http://openmesh.org/svnrepo/OpenMesh@1089 fdac6126-5c0c-442c-9429-916003d36597