Merge branch 'po/object-id'

Conversion from uchar[20] to struct object_id continues. * po/object-id: sha1_file: rename hash_sha1_file_literally sha1_file: convert write_loose_object to object_id sha1_file: convert force_object_loose to object_id sha1_file: convert write_sha1_file to object_id notes: convert write_notes_tree to object_id notes: convert combine_notes_* to object_id commit: convert commit_tree* to object_id match-trees: convert splice_tree to object_id cache: clear whole hash buffer with oidclr sha1_file: convert hash_sha1_file to object_id dir: convert struct sha1_stat to use object_id sha1_file: convert pretend_sha1_file to object_id