Adds metadata log, and command.
Note that unsetting field values seems to currently be broken.
And in general this has had all of 2 minutes worth of testing.
This commit was sponsored by Julien Lefrique.
Note that on Windows a remote with a path like /home/foo/bar
is interpreted by git as being some screwy relative path (relative to what
exactly seems ill-defined -- it seemed relative to C:\Program Files\Git\ in
my tests!) So no attempt has been made to handle such a path sanely, just not
to crash when encountering it.
Note that "C:\\foo" </> "/home/foo/bar" yields /home/foo/bar even though
that is not absolute! I don't know what to make of all this,
except that I will be very happy when this crock of **** vanishes from
the face of the earth.
