builtin-notes: Add "list" subcommand for listing note objects
"git notes list" will list all note objects in the current notes ref (in the
format "<note object> <annotated object>"). "git notes list <object>" will
list the note object associated with the given <object>, or fail loudly if
the given <object> has no associated notes.
If no arguments are given to "git notes", it defaults to the "list"
subcommand. This is for pseudo-compatibility with "git tag" and "git branch".
The patch includes tests verifying correct behaviour of the new subcommand.
Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>