Squashed 'src/lib/vector_clock/' content from commit a32a9cb

git-subtree-dir: src/lib/vector_clock
git-subtree-split: a32a9cbc42b5aef477f62886bb75667b22bf2e9f
Merge commit '44fa4826449a4c66319dad69ac4c622fec04a95a' as 'src/lib/vector_clock'
Now using the external project version of bounded_version_vector. Also, kill -lto for now, since it's causing nothing but trouble.