3DFACE: spelling corrections in Doxygen comments.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
global.h: removed the DEBUG #define.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
3DFACE: compatibility now according to DXF R13.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
Synchronizing po/libdxf.pot.

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