mirage/irmin 0.12.0 on GitHub

Depends on irmin-watcher 0.2.0 to use portable file-system watches
(fsevents on OSX or inotify on Linux) to replace the slow and CPU
intensive file-system polling that was the default (#380, @samoht)
Do not use Lwt_unix.fork in the tests anymore (#383, @samoht)
Switch from Stringext to Astring (#382, @samoht)
Fix regression in the tests for using Git over HTTP (#376, @samoht)
Catch top-level exceptions in watch callbacks (#375, @samoht)
Fix merge of assoc list with no common ancestor (#374, @samoht)
Improve documentation for Git bare repositories (#363, @kayceesrk)
New functor Make_with_metadata to customize the type of the
nodes metadata (#364, @samoht)
Remove mentions of private modules from the public interface
(#364, @samoht)