Merge branch 'bc/object-id'

Merge branch 'bc/object-id'

The "unsigned char sha1[20]" to "struct object_id" conversion
continues.  Notable changes in this round includes that ce->sha1,
i.e. the object name recorded in the cache_entry, turns into an
object_id.

It had merge conflicts with a few topics in flight (Christian's
"apply.c split", Dscho's "cat-file --filters" and Jeff Hostetler's
"status --porcelain-v2").  Extra sets of eyes double-checking for
mismerges are highly appreciated.

* bc/object-id:
  builtin/reset: convert to use struct object_id
  builtin/commit-tree: convert to struct object_id
  builtin/am: convert to struct object_id
  refs: add an update_ref_oid function.
  sha1_name: convert get_sha1_mb to struct object_id
  builtin/update-index: convert file to struct object_id
  notes: convert init_notes to use struct object_id
  builtin/rm: convert to use struct object_id
  builtin/blame: convert file to use struct object_id
  Convert read_mmblob to take struct object_id.
  notes-merge: convert struct notes_merge_pair to struct object_id
  builtin/checkout: convert some static functions to struct object_id
  streaming: make stream_blob_to_fd take struct object_id
  builtin: convert textconv_object to use struct object_id
  builtin/cat-file: convert some static functions to struct object_id
  builtin/cat-file: convert struct expand_data to use struct object_id
  builtin/log: convert some static functions to use struct object_id
  builtin/blame: convert struct origin to use struct object_id
  builtin/apply: convert static functions to struct object_id
  cache: convert struct cache_entry to use struct object_id