• Convert testing to use docker with updated git versions
• Fix numerous places where quoting was incorrect causing path name collisions
• Fix pull-force test to deal with git not defaulting to merges on pulls after 2.33
• Fix issue where docker tests didn't work with git 2.30 or higher because of
  increased permission scrutiny.
• Update readme to say this tools is in production environments
• Update readme to use internet archive for old articles about subrepo no longer
  available on their original source