First of all, the memory sizing thing.  We need to look at the number
of cells in the `reg' property and use *all* of them.  The current
code that terminates after an empty slot is just broken.  (Note that
MacOS boots just fine with the DIMMs in the `wrong' slots, FWIW.)

I attempted to run 16bpp mode, by hacking ofb.c.  It turns out that
rasops has a problem on the Mac with 16bpp mode that causes all the
text to come out Very Strangely.  It almost looks like an endianness
problem.  In addition, Xmacppc is hard-coded to 8bpp mode.  This
probably isn't difficult to fix.

Also, the colormap stuff appears to be broken.  I don't know why.
Whenever I run abiword or xscreensaver, colors used by other apps
(like the window manager) are permanently toasted.