Split off from clue/graph

[clue]

See also graphp/graph#117

[clue]

Use https://gist.github.com/emiller/6769886 to rewrite the relevant paths to a target directory, then run a subdirectory-filter to only keep the target directory:

git clone git@github.com:clue/graph.git plaintext
cd plaintext
wget https://gist.githubusercontent.com/emiller/6769886/raw/8899e5540f65dd95b79250e637d71ca0cde6f269/git-mv-with-history
mkdir lib/Loader # needed temporarily to rewrite outdated paths
bash git-mv-with-history lib/Fhaculty/Graph/Loader=target/src tests/Fhaculty/Graph/Loader=target/tests lib/Loader=target/src
git filter-branch -f --subdirectory-filter target/ -- --all