evolve: run in a single transaction
This speeds up `hg evolve --all` of a stack of 24 commits in the hg
repo from 11.5s to 3.7s (3x). As can be seen in the tests, it also
avoid some warnings about transiently unstable commits.
mkdir -p html
cp index.html html/
cp *.css html/
cp *.js html/
cp -R img html/
cp -R graphviz-images/ html/
netlify deploy