STYLE: according to R10..R14.

Signed-off-by: bert <bert.timmerman@xs4all.nl>
STYLE: addeddxf_style_is_shape_file().

Signed-off-by: bert <bert.timmerman@xs4all.nl>
STYLE: added dxf_style_is_text_vertical().

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