first CD where possible. We then make 2 copies of this, one with
non-US and one without. Useful for people wanting to create non-US and
US-safe CD sets without having to spend so much disk space.
Side-effects: The CD tress are now $(DIR)/CD<foo> instead of
$(DIR)/<foo>
Raphaël Hertzog
Anne Bezemer
Jim Westveer
Ben Collins
Steve McIntyre