	Register given remote as TopGit-controlled. This will create
	the namespace for the remote branch bases and teach 'git fetch'
	and 'git push' to operate on them. (Do NOT use 'git push --all'
	for your pushes - plain 'git push' will do the right thing.)

	It takes a mandatory remote name argument, and optional
	'--populate' switch - use that for your origin-style remote,
	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' to look at
	branches of this remote for updates by default.

