Do not die on unknown material type

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36591 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Remove username from header

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36592 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Remove username from header

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36593 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e