new xli snapshot, fixes -fillscreen bug with -onroot

[Smarasderagd]

I finally got around to fixing a problem with unsigned arithmetic that
was resulting in a blank screen when using -fillscreen (and occasioanlly
with -fullscreen) and -onroot.  Thanks to Yoshihiko Sarumaru who tracked
down the problem and sent me a fix!  The new snapshot is available at
http://pantransit.reptiles.org/prog/xli/xli-2005-09-04.tar.gz