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.
