	Remove a TopGit-controlled topic branch of given name
	(required argument). Normally, this command will remove
	only empty branch (base == head); use '-f' to remove
	non-empty branch.

	The '-f' option is also useful to force removal of a branch's base, if
	you used 'git branch -D B' to remove the branch B, and then certain
	TopGit commands complain, because the base of branch B is still there.

	Currently, this command will _NOT_ remove the branch from
	the dependency list in other branches. You need to take
	care of this _manually_. This is even more complicated
	in combination with '-f', in that case you need to manually
	unmerge the removed branch's changes from the branches
	depending on it.

	TODO: '-a' to delete all empty branches, depfix, revert

