Merge branch 'nd/columns'

Merge branch 'nd/columns'

A couple of commands learn --column option to produce columnar output.

By Nguyễn Thái Ngọc Duy (9) and Zbigniew Jędrzejewski-Szmek (1)
* nd/columns:
  tag: add --column
  column: support piping stdout to external git-column process
  status: add --column
  branch: add --column
  help: reuse print_columns() for help -a
  column: add dense layout support
  t9002: work around shells that are unable to set COLUMNS to 1
  column: add columnar layout
  Stop starting pager recursively
  Add column layout skeleton and git-column