RAY: changed the return type for dxf_ray_read().

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

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

Signed-off-by: bert <bert.timmerman@xs4all.nl>
RAY: according to R10..R14.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
RAY: test for minimum DXF version.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
OLEFRAME: test for minimum DXF version.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
MTEXT: test for minimum DXF version.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
ELLIPSE: corrected test for minimum DXF version.

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