You can clone with
HTTPS or Subversion.
It appears all templates used by the bookmarks app are missing. I'm not sure if this is intentional or not but I believe it would be a good idea to put this in so people have a sane default to work with and an example of how to make their own custom templates.
Make some :)
I haven't had time lately to make some which is why they're not there but I'd gladly accept a patch.