LINE: according to R10 ... R14.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
ELLIPSE: in version > R13 an ellipse has no thickness.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
3DFACE: updated doxygen comments.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
3DFACE: test if edges are invisible.

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