The change in the previous commit was a silly case of not thinking
things through, not realizing that the .data range moved to Core.obj was
nowhere near the beginning of the section as it should be. g_game has
been moved back into Jet2.obj (time will tell if this is correct) and a
missed data strucure at the beginning of .data (where it ought to be)
now makes up Core.obj's .data portion.
We can now create a fresh Ghidra project, import the JSRF executable
into it, import symbols into it, delink object files from it, and then
decompile with objdiff. Just needs some documentation.