	Register the given remote as TopGit-controlled. This will create
	the namespace for the remote branch bases and teach `git fetch`
	to operate on them. However, from TopGit 0.8 onwards you need to
	use `tg push`, or `git push --mirror`, for pushing
	TopGit-controlled branches.

	`tg remote` takes an optional remote name argument, and an
	optional '--populate' switch.  Use '--populate' for your
	origin-style remotes: it will seed the local topic branch system
	based on the remote topic branches.  '--populate' will also make
	`tg remote` automatically fetch the remote, and `tg update` look
	at branches of this remote for updates by default.

