- Make targets explicit b7ad08df84.
- Get rid of Vfile e73fd90b65.
Without vfile we need some new concepts to avoid parsing the requires
file multiple times and with vfile it's annoying to specify the
dependencies by hand.
Will leave that for future work. Just use memoize where it make sense,
for instance when we read the result from only the current directory
(for instance the ocamldep stuff).