	Create a new TopGit-controlled topic branch of the given name
	(required argument) and switch to it.  If no dependencies are
	specified (by extra arguments passed after the first one), the
	current branch is assumed to be the only dependency.

	After `tg create`, you should insert the patch description into
	the '.topmsg' file, which will already contain some prefilled
	bits.  You can set the 'topgit.to', 'topgit.cc' and 'topgit.bcc'
	git configuration variables (see `man git-config`) in order to
	have `tg create` add these headers with the given default values
	to '.topmsg'.

	The main task of `tg create` is to set up the topic branch base
	from the dependencies.  This may fail due to merge conflicts.
	In that case, after you commit the conflict resolution, you
	should call `tg create` again (without any arguments); it will
	detect that you are on a topic branch base ref and resume the
	topic branch creation operation.

	In an alternative use case, if '-r BRANCH' is given instead of a
	dependency list, the topic branch is created based on the given
	remote branch.

	You can use a different command instead of the default 'git merge'
	when updating or creating branches (see `tg update` for a full
	description). For example, if you want to 'git merge -s ours' the
	dependencies into the new branch, invoke the command with
	(the custom message is to attract attention):

	--this-with='git merge -s ours -m "merge -s ours"'

