	Show overview of all TopGit-tracked topic branches and their
	up-to-date status ('>' marks the current topic branch,
	'0' marks that it introduces no own changes,
	'l'/'r' marks that it is local-only or has remote mate,
	'L'/'R' marks that it is ahead/out-of-date wrt. its remote mate,
	'D' marks that it is out-of-date wrt. its dependencies,
	'!' marks that it has missing dependencies (even recursively),
	'B' marks that it is out-of-date wrt. its base).

	This can take long time to accurately determine all the relevant
	information about each branch; you can pass '-t' to get just
	terse list of topic branch names quickly. Alternately, you can
	pass '--graphviz' to get a dot-suitable output to draw a dependency
	graph between the topic branches.

	TODO: Speed up by an order of magnitude
	TODO: Text graph view

