SECTION: implemented DXF_DEBUG macros.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
SECTION: make string translatable.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
SECTION: use DxfFile struct.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
SECTION: check for NULL pointers.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
SECTION: correction in a Doxygen comment.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
SEQEND: correction in a Doxygen comment.

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