Process variable imports

Tested with the demo of God Eater Burst (finally realized there was a demo.)

Lots of help from MIPS ABI docs and Linux MIPS code.  Also checked JPCSP, but its code looks very questionable in this area (it seems to compare R_MIPS_32 to MIPS cpu opcodes??)  Anyway, tried to leave generous comments where needed.

This fixes the memory access warnings in God Eater Burst's demo, and I hope it will improve Tales of the World: Radiant Mythology 2 (and 3?)  I didn't go past the relocation failure in the God Eater Burst demo before, but it seems to run correctly.

-[Unknown]