journal: add dirstate tracking
Note that now the default action for `hg journal` is to list the working copy
history, not all bookmarks. In its place is the `--all` switch which lists all
name changes recorded, including the name for which the change was recorded on
each line.
Locking is switched to using a dedicated lock to avoid issues with the dirstate
being written during wlock unlocking (you can't re-lock during that process).