Merge branch 'fc/zsh-completion'

Zsh autocompletion (in contrib/) update.

* fc/zsh-completion: (29 commits)
  zsh: update copyright notices
  completion: bash: remove old compat wrappers
  completion: bash: cleanup cygwin check
  completion: bash: trivial cleanup
  completion: zsh: add simple version check
  completion: zsh: trivial simplification
  completion: zsh: add alias descriptions
  completion: zsh: improve command tags
  completion: zsh: refactor command completion
  completion: zsh: shuffle functions around
  completion: zsh: simplify file_direct
  completion: zsh: simplify nl_append
  completion: zsh: trivial cleanup
  completion: zsh: simplify direct compadd
  completion: zsh: simplify compadd functions
  completion: zsh: fix splitting of words
  completion: zsh: add missing direct_append
  completion: fix conflict with bashcomp
  completion: zsh: fix completion for --no-.. options
  completion: bash: remove zsh wrapper
  ...

diff --cc contrib/completion/git-completion.bash
Simple merge

diff --cc t/t9902-completion.sh
Simple merge