Updates to ide-cd to be able to dma to any address (almost). The new
work-horse is cdrom_newpc_intr(). IMHO, it's much cleaner than the old
interrupt handlers, we can basically kill all three of them in the
future and just use this one. You had a lot of bugs in there :-)

If you want in-depth let me know, but I'm pretty beat right now and too
lazy to do the write up. Lots of cleanups, lots of fixes. pre-transform
is a prep function now.