Add a simple script to generate a sort of build manifest.

For now this just dumps data to stdout and has no options. Likely
this should be rolled into the fetch script and renamed accordingly.
Get manifest_gen.sh working for a few edge cases previously not considered.
Moar edge cases in manifest_gen.sh.

I screwed up the recursion on the last push too. Test test test.
Merge branch 'master' into measured