* np/dreflog:
show-branch -g: default to the current branch.
Let git-checkout always drop any detached head
Enable HEAD@{...} and make it independent from the current branch
scan reflogs independently from refs
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