Keeping these definitions separate from the implementations will help
generating man pages for the executables without putting _all_ of the
dependencies into the build-dependencies.
Before this change, when running `git add-coauthor` without an existing
`~/.git-coauthors` file, the program would print an error message on
stderr that the file did not exist.
It would then create the file with the newly added co-author in it.
That message seemed unnecessary and so it has now been removed.
Co-authored-by: Maria Hansson <mariahansson92@hotmail.com>
Martin Frost
Martin Frost