	Show overview of all TopGit-tracked topic branches and their
	up-to-date status ('>' marks the current topic branch,
	'0' indicates that it introduces no changes of its own,
	'l'/'r' indicates respectively whether it is local-only or has a remote mate,
	'L'/'R' indicates respectively if it is ahead or out-of-date with respect to its remote mate,
	'D' indicates that it is out-of-date with respect to its dependencies,
	'!' indicates that it has missing dependencies [even if they are recursive ones], and
	'B' indicates that it is out-of-date with respect to its base).

	This can take a long time to accurately determine all the
	relevant information about each branch; you can pass '-t' to get
	just a 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.

	You can also use the '--sort' option to sort the branches using
	a topological sort.  This is especially useful if each
	TopGit-tracked topic branch depends on a single parent branch,
	since it will then print the branches in the dependency order.
	In more complex scenarios, a text graph view would be much more
	useful, but that has not yet been implemented.

	The --deps option outputs dependency information between
	branches in a machine-readable format.  Feed this to `tsort` to
	get the output from --sort.

	Options:
	  -i		Use TopGit metadata from the index instead of the branch
	  -w		Use TopGit metadata from the working tree instead of the branch

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

