fix comparison with invalid iterator

refs #2263

git-svn-id: http://openmesh.org/svnrepo/OpenMesh@1177 fdac6126-5c0c-442c-9429-916003d36597
fix 32/64-bit bug on windows (analyzer and synthesizer reads with unsigned int -> 32bit, writer writes size_t -> possible 64-bit)

git-svn-id: http://openmesh.org/svnrepo/OpenMesh@1178 fdac6126-5c0c-442c-9429-916003d36597
add unittest for vdpm (read and write/read)

closes #2263

git-svn-id: http://openmesh.org/svnrepo/OpenMesh@1179 fdac6126-5c0c-442c-9429-916003d36597
fix cppcheck warning

git-svn-id: http://openmesh.org/svnrepo/OpenMesh@1180 fdac6126-5c0c-442c-9429-916003d36597