WIP: [kicad-parser] write a KicadBoard

[mkovaxx]

No description provided.

[mkovaxx]

@bschwind The current data model seems to assume that the FootprintX and GraphicX structures are identical.
That seems not to be the case:
https://dev-docs.kicad.org/en/file-formats/sexpr-intro/index.html#_footprint_graphics_items
https://dev-docs.kicad.org/en/file-formats/sexpr-intro/index.html#_graphic_items

[bschwind]

The current data model seems to assume that the FootprintX and GraphicX structures are identical.
That seems not to be the case:

Yep, let's keep these as separate types.

[bschwind]

Looking pretty good so far! A few questions:

• What's the scope for this PR, or when do we consider it "done"? When we can write out a fully-functioning *.kicad_pcb file?
• It would make sense to have a write_to_file<P: AsRef<Path>>(file: P) convenience function
• Pretty printing of the S-expressions would be nice, maybe the sexp crate doesn't support that though
• Just for fun I tried exporting a kicad_pcb file by reading the sample.kicad_pcb file and immediately serializing it again. When trying to read it into KiCAD, I got:

[bschwind]

Should this instead be KicadPcb? I think my original plan was for KicadBoard to hold the actual board data like copper, footprints, silkscreens, etc, while KicadPcb would hold a KicadBoard, as well as extra data like the version and other metadata.

[bschwind]

Suggested change

	cons_s("start", point_to_sexp(circle.center_point)),
	cons_s("center", point_to_sexp(circle.center_point)),

[bschwind]

I might call this orientation_to_sexp or transform_to_sexp, as I expected position to just mean an XY coordinate.