amend: add -D/--current-date option, just like mq's qrefresh has Carefully designed so we can easily add -D to other changeset-creating commands (probably anything that takes -d), and so that we can add -U/--current-user as well. When that's done, the date and user options should be very similar to those in MQ.

amend: explicitly test -d option

amend: in tests, do not rely on defaults -- always use explicit -d Having a default -d option will make it hard to test -D/--current-date, which is coming shortly: presence of -d overrides -D, just like with mq's qrefresh.