release() and build_win() use --compact-vignettes=both

[krlmlr]

to avoid WARNINGs with the built package.

[hadley]

I've never seen these notes. Can you provide more details? What system requirements are necessary to be able to compact vignettes?

[krlmlr]

It's even a warning, and happens with PDF vignettes.

http://win-builder.r-project.org/48l69H500MSZ/00check.log was created with 3835a87 and contains:

* checking sizes of PDF files under 'inst/doc' ... WARNING
  'gs+qpdf' made some significant size reductions:
     compacted 'tikzDevice.pdf' from 1137Kb to 493Kb

[hadley]

Hmmm, if it needs other software, we definitely shouldn't do this unconditionally. Could you please add a check for the presence of the needed software?

[krlmlr]

Didn't think about that. Adding an args argument to release() would be simpler and potentially more useful, would you prefer that? (build_win() already has one.)

[hadley]

Yeah, that sounds good.