Merge branch 'maint'

* maint:
  Don't package the git-gui credits file anymore
  git-gui: Allow 'git gui version' outside of a repository
  git-gui: Revert "git-gui: Display all authors of git-gui."
  git-gui: Revert "Don't modify CREDITS-FILE if it hasn't changed."
  git-gui: Allow committing empty merges

diff --cc Makefile
Simple merge