Move all rebase.* configuration variables to a separate file in order to
remove duplicates, and include it in config.txt and git-rebase.txt. The
new descriptions are mostly taken from config.txt as they are more
verbose.
Signed-off-by: Liam Beguin <liambeguin@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>