Merge branch 'jt/rev-list-z'

Merge branch 'jt/rev-list-z'

"git rev-list" learns machine-parsable output format that delimits
each field with NUL.

* jt/rev-list-z:
  rev-list: support NUL-delimited --missing option
  rev-list: support NUL-delimited --boundary option
  rev-list: support delimiting objects with NUL bytes
  rev-list: refactor early option parsing
  rev-list: inline `show_object_with_name()` in `show_object()`