Use system memory mapping to resemble PS2 memory about play-

[jpd002]

There's indeed a lot of space for improvement regarding memory accesses in the emulator. The JIT blocks generated for VU microprograms already access VU memory directly, but there's nothing for the EE and IOP blocks yet. I'll look into what PPSSPP and Dolphin do and see how something similar could be implemented in Play!

How about this now?

[jpd002]

There's been some improvements to this done 3 years ago: the EE and IOP now have some kind of mapping table they can use from JITed code to access memory directly without going through a function call.

There's still space for improvement since there's a test to see if the entry in the table is valid that could probably be removed. I don't think this is a priority as there are other bottlenecks that would be more interesting to tackle.