git subrepo pull packages/CLI11

subrepo:
  subdir:   "packages/CLI11"
  merged:   "2b059cbdb"
upstream:
  origin:   "git@github.com:CLIUtils/CLI11.git"
  branch:   "master"
  commit:   "2b059cbdb"
git-subrepo:
  version:  "0.4.1"
  origin:   "git@github.com:ingydotnet/git-subrepo.git"
  commit:   "a04d8c2"

Also add 'required' option for script filename