Review DXF format

The attachment is from Lectra indicating what the file must contain in order for it to be directly imported. It might be worth double checking that we include everything that is required.

[DXF format - So that Modaris can import a DXF file.pdf](https://github.com/aharwood2/JBlockCreator/files/3685365/DXF.format.-.So.that.Modaris.can.import.a.DXF.file.pdf)
