First step with .obj file format

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30848 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Fix for #3949: use construction index rather than output order

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30849 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e