Tried to convert the ppc32_microcode assembly from 0.2.8-RC2 to C.

MUST BE VALIDATED
The interrupt/exception vectors are still in assembly since I don't know
how to generate a rfi return in C.
Inspected (and fixed) the ppc32_microcode source.
Minor changes to README.md.

Finally! I'm happy with this result. =)
Begone evil default tab+space behaviour of emacs... >.>
(note that mixing tabs and spaces isn't evil, just inconvenient)