fix copy and pase bug


git-svn-id: https://geuz.org/svn/gmsh/trunk@18418 59c8cabf-10d6-4a28-b43f-3936b85956c4
handle errors more gracefully


git-svn-id: https://geuz.org/svn/gmsh/trunk@18419 59c8cabf-10d6-4a28-b43f-3936b85956c4
fix memory leaks


git-svn-id: https://geuz.org/svn/gmsh/trunk@18420 59c8cabf-10d6-4a28-b43f-3936b85956c4