Conflicts:
	vcsh

Conflicts:
	vcsh

permit "-b <branch>" to come later on the command line

Also fixed the last hardcoded reference to the master branch.

Also, refactor list_tracked_by() to re-use code

github: Closes richih/vcsh#142

Avoid spawning `cut` and speed recursive mode up from "takes several seconds on a
current machine" to "instant".

Thanks to Thorsten Glaser.

github: Fixes richih/vcsh#123

This is the API for an optional branch selection for `vcsh clone`. It is
basically inspired by `git clone [-b|--branch <name>] <remote>`. I could
have used the long option `--branch` too but vcsh only uses short ones.

This will create and checkout a local branch named after the upstream
branch. It will also gracefully behave for the default `master' branch
and consistently show the same message:

Switched to a new branch '$VCSH_BRANCH'