"Length" is more natural than "height" for flat plate materials.
Renames the field on OpenNest.Geometry.Size, Box.Height property,
and all references across 38 files.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Move DxfImporter, DxfExporter, NestReader, NestWriter, ProgramReader,
and Extensions into a new OpenNest.IO class library. The WinForms project
now references OpenNest.IO instead of ACadSharp directly.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
