Merge in "box packer" script

[trickeydan]

@kierdavis wrote a box packing script for kit packing. We should merge it in here.

[kierdavis]

The script is currently here: https://gist.github.com/kierdavis/ddd6da1c76119841264f20cdaee1958d

Note that this isn't a matter of downloading and committing the file - it really needs a lot of polish and should talk directly to the rest of this package to operate the inventory rather than calling out to subcommands. I'd recommend the script be used as a proof-of-concept/reference implementation for creating a new sr pack-kit command (or something similar).

[trickeydan]

We used this again for SR2022.

[PeterJCLaw]

One thing which would be good to do before merging into the shared tools would be to separate out the specification for what should go in the box from the implementing code. Otherwise we end up with tooling that's tied to a specific year's kit.

[trickeydan]

separate out the specification for what should go in the box from the implementing code.

So I don't think we can put that in the inventory repo yet? For the same reason as we can't add a README?

We could bake a definition file into this package but that doesn't feel right.

[PeterJCLaw]

I think there's some space in the .meta directory which we could put things like this -- I believe that directory isn't searched for part files (only templates), so ought to be able to not break things.