[arch-releng] our core-dual images are too big

[Dieter Plaetinck]

the size of core-dual iso has been over 700MB for a while.
the last one is 738MB.
See http://releng.archlinux.org/isos/2011.04.30/

what would be the best way to fix this? different archiso2dual
parameters? different compression somewhere? revised packagelist?
moving some packages out of core? [is anyone aware of noticeable size
increases of the core repo or core packages?]

Dieter