Added lineWeight support to dxf exporter

[xavi-]

This PR exposes the ability to change the Line Weight of lines drawn in a particular layer. This is a feature that was added in DXF R2000 and is supported by other DXF libraries. Ex: https://ezdxf.readthedocs.io/en/stable/concepts/lineweights.html

The hope was to also make the DXF exporter in closer parity with the SVG exporter, specifically in terms of strokeWidth

[xavi-]

@microsoft-github-policy-service agree

[danmarshall]

Wow, thank you so much! Is this backward compatible with older DXF versions?

[xavi-]

To be honest, I'm not sure. According to a gemini result, DXF R2000 came out in March 1999, though it might be confusing DXF R2000 with AutoCAD 2000 and/or DWG 2000 (or maybe they all came out at the same time! I'm not sure). In either case, support for Line Weight seems fairly well established

Also, I think, I read some where that most DXF readers ignore codes that they don't recognize so it should be backwards compatible

[xavi-]

Okay a bit more research and it seems DXF AC1015 is synonymous with DXF R2000, which indeed came out in March 1999.

See https://images.autodesk.com/adsk/files/autocad_2012_pdf_dxf-reference_enu.pdf (page 11)

[danmarshall]

Thanks for doing the research. I think then that we can remove enableLineWeight and just look for the existence of a lineWeight to add the header.