fix cleanup in d'tor

git-svn-id: http://openmesh.org/svnrepo/OpenMesh@1048 fdac6126-5c0c-442c-9429-916003d36597
- decimater (incremental & mc) doesn't require normals anymore
- mod normalFlipping & normalDeviation computes normals, if mesh hasn't normals
- add 2 decimater unittest (decimating with normalFlipping and initialize all modules)

git-svn-id: http://openmesh.org/svnrepo/OpenMesh@1049 fdac6126-5c0c-442c-9429-916003d36597
fix mod name

git-svn-id: http://openmesh.org/svnrepo/OpenMesh@1050 fdac6126-5c0c-442c-9429-916003d36597