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