feat idea: arXiv submission helper

[joshuahhh]

Looks like it's a bit tricky to submit a paper to arXiv from Living Papers.

• You need to extract source files from .temp/latex, preferably without build output files. (Although apparently some build output, like .bib, is desired...)
• You need to do a bit of directory structure rearrangement, if .temp/latex/index.tex accesses figures from assets. Hidden directories are deleted!

Seems like it wouldn't be too hard to have an arXiv-submission output format, or helper script, or something.

Other fun things this format/helper could do:

• Strip out comments from the tex file, since it gets archived.
• Remove unused figures, since they get archived too.

Some info on what arXiv is looking for in a TeX submission.

[jheer]

On a related note, you can use the pdf: false option for latex output to generate the source files instead of the compiled PDF.