properties.set documented `transparency` but never read it, nothing reported it,
and DXF dropped group 440. Fixes#132.
- properties.set takes "ByLayer", "ByBlock" or a percentage 0..90 (a number or
"50"/"50%"); anything else (out of range, NaN, junk) is an error and leaves
the selection unchanged.
- properties and drawing.inspect / drawing.entities report it in the same form.
- Properties palette: the Transparency row is a menu (ByLayer, ByBlock, a
0..90 percentage) that acts through properties.set.
- DXF: entities write 440 unless ByLayer (ByBlock 0x01000000, a percentage its
alpha | 0x02000000, the alpha mapping layers use); the reader parses it back,
any other value reads as ByLayer.
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Valentin KleinandClaude Opus 5.5
3fe93806b7