OLEFRAME: implemented DXF_DEBUG macros.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
OLEFRAME: make strings translatable.

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

Signed-off-by: bert <bert.timmerman@xs4all.nl>
MTEXT: corrections in Doxygen comments.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
OLEFRAME: check for NULL pointers and do basic checks.

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