Merge branch 'np/dreflog' into next

Merge branch 'np/dreflog' into next

* np/dreflog:
  add reflog when moving HEAD to a new branch
  create_symref(): do not assume pathname from git_path() persists long enough
  add logref support to git-symbolic-ref
  move create_symref() past log_ref_write()
  add reflog entries for HEAD when detached
  enable separate reflog for HEAD
  lock_ref_sha1_basic(): remember the original name of a ref when resolving it
  make reflog filename independent from struct ref_lock
  Compute accurate distances in git-describe before output.
  Update describe documentation.
  Teach git-describe to display distances from tags.
  git-blame --porcelain: quote filename in c-style when needed.
  git-blame --incremental
  Don't force everybody to call setup_ident().
  git-log -g --pretty=oneline should display the reflog message
  Document --check option to git diff.
  Allow the tag signing key to be specified in the config file