I've gotten the bs branch to build everything again. Was not trivial, the diff is over 7000 lines.

Had hoped this was a mechanical enough conversion it would not introduce many bugs, but the test suite quickly found a lot of problems. So that branch is not ready for merging yet.

I'm considering making a library that's like filepath but for RawFilePath. That would probably speed git-annex up by another 5% or so, in places where it currently has to convert back to FilePath.