Update on FPU emulation

[Igor Khavkine]

Ok, I've improved and actually tested my patch for FPU emulation
in oskit-mach. You can get it at http://alcor.concordia.ca/~i_khavki/.
Now there are still problems like some instructions are not interpreted
properly and generate an illegal instruction exception. I'm still not
sure why that's happening and whether the emulator's instruction decoder
or my changes are at fault.

Also note that it's a fairly big patch, that's because I've also been messing
with my oskit-mach tree trying to eliminate redundancy with respect to what's
provided by oskit.

Igor