On cancelled orders, you can click on the "New copy of Quotation"
button. This will create a new revision of the quotation, with the same
base number and a '-revno' suffix appended. A message is added in the
chatter saying that a new revision was created.

In the form view, a new tab is added that lists the previous revisions,
with the date they were made obsolete and the user who performed the
action.

The old revisions of a sale order are flagged as inactive, so they don't
clutter up searches.
