DONUT: avert using dxf_polyline_write_lowlevel()
and dxf_vertex_write_lowlevel().

Signed-off-by: bert <bert.timmerman@xs4all.nl>
POLYLINE: removed dxf_polyline_write_lowlevel().

Signed-off-by: bert <bert.timmerman@xs4all.nl>
VERTEX: removed dxf_vertex_write_lowlevel().

Signed-off-by: bert <bert.timmerman@xs4all.nl>