This was easier than I expected - just add an optional buttons="1"
attribute to cutscenes.xml. It's treated like the speaker attribute -
it's only there as context for the translator, and for the cutscene
test.
Due to rebasing messiness and diff noise, it's probably best if pull
requests either don't sync all the language files at all (and only
modify the English ones) OR only do it as a final commit. It's still
something we need to figure out, lol.
For some reason they all have their executable bits set. Presumably this
is because they were made on an NTFS system where every file is
executable (which doesn't sound secure at all but that's another story).