Bookmarks: Add the bookmarks extension
Mercurial bookmarks are local moveable pointers to changesets.
If you commit a changeset that is based on a changeset that has a
bookmark on it, the bookmark is forwarded to the new changeset.
Thanks to Ian Dees, Ronny Pfannschmidt for their patches,
Thanks to ronny, tonfa, prianha, mpm, #mercurial for their comments
and their support that helped me to get things done.
workingfilectx.date = (1000, 0)