Fix for c++11 call to pointer to member function of type 'VertexIter ()' drops 'const' qualifier (Thanks to Ronald Richter and Kenshi Takayama for the fix)

git-svn-id: http://openmesh.org/svnrepo/OpenMesh/trunk@1021 fdac6126-5c0c-442c-9429-916003d36597