Add date and identifier arguments to burn test generator

[sethfischer]

I've created a custom burn test generator which adds the options to etch the date and/or an identifier onto the parts. The additional options are:

• --date: add current date etching to each piece
• --id: add identifier etching to each piece

Example command:

boxes BurnTestCustom --date=1 --id="my identifier"

Example output:

If users would find this feature useful (or variations on this feature) I'd be happy to submit a pull request.

[florianfesti]

This looks useful. Especially for people with multiple laser cutters but also for comparing different settings. Merging these changes in the upstream generator is very welcome.