The disks were using ProDOS v2.0.3, which requires an enhanced //e.
ProDOS v1.8 will run on a ][+. We lose the nicer QUIT handler, but
now the demos will run on a plain 6502 system (verified with
AppleWin).
Made some minor optimizations to the Applesoft BASIC code driving
the slide show. Improved the speed from 3.7 fps to 4.3 fps.
(With the 65816 decoder, it went from 6 to 7.7 fps.)
