DXF: Keep track of object visibility and paper/model space
|Reported by:||Alan Thomas||Owned by:||warmerdam|
Split out from #4369:
Added new attributes for features:
- "PaperSpace" -> Absent or "0" means model space, "1" means paper space.
- "Invisible" -> Indicates the object visibility: "0" = visible, "1" = invisible
Paper space uses a completely different coordinate system from model space, so I wonder if we could even just ignore entities in paper space, or alternatively shove them in a different OGR feature layer or something.