Merge branch 'rs/name-rev-memsave'

Memory footprint and performance of "git name-rev" has been improved. * rs/name-rev-memsave: name-rev: sort tip names before applying name-rev: release unused name strings name-rev: generate name strings only if they are better name-rev: pre-size buffer in get_parent_name() name-rev: factor out get_parent_name() name-rev: put struct rev_name into commit slab name-rev: don't _peek() in create_or_update_name() name-rev: don't leak path copy in name_ref() name-rev: respect const qualifier name-rev: remove unused typedef name-rev: rewrite create_or_update_name()