The result name is taken by other libs hence it breaks `jbuilder utop`. Hence we
simply move it our stdlib overlay. The -open flag is used to avoid having to
modify vendored code.
Before, jbuilder used to stop its execution after an error was
encountered. Now it continues until all branches have been explored.
To implement this feature, Future was rewritten as a Fiber module with
a simpler semantic.
This patch contains various other refactorings.
Rudi Grinberg
Jérémie Dimino
Jeremie Dimino