notes: add shorthand --ref to override GIT_NOTES_REF Adds a shorthand option that overrides the GIT_NOTES_REF variable, and hence determines the notes tree that will be manipulated. It also DWIMs a refs/notes/ prefix. Signed-off-by: Thomas Rast <trast@student.ethz.ch> Acked-by: Johan Herland <johan@herland.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>