Conflicts:
	vcsh

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

May fix https://github.com/RichiH/vcsh/issues/122

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=760882

README: Using a `repo_name` instead of `foo`

I get lost within all of those meaningless names.
It is useful to give things meaningful names, especially in documentation.

typo `that you cat track` -> `that you can track`