Merge branch 'kn/for-each-branch'

Update "git branch" that list existing branches, using the
ref-filter API that is shared with "git tag" and "git
for-each-ref".

* kn/for-each-branch:
  branch: add '--points-at' option
  branch.c: use 'ref-filter' APIs
  branch.c: use 'ref-filter' data structures
  branch: drop non-commit error reporting
  branch: move 'current' check down to the presentation layer
  branch: roll show_detached HEAD into regular ref_list
  branch: bump get_head_description() to the top
  branch: refactor width computation

diff --cc Documentation/git-branch.txt
Simple merge

diff --cc builtin/branch.c
Simple merge