add region detection support (port 0x3F)

[ITotalJustice]

https://www.smspower.org/Development/RegionDetection

https://www.smspower.org/Development/PeripheralPorts#Port3FIOPortControl

so games will write to port $3F and then read back the value. if the same value is read back, then it is not japanese system

[ITotalJustice]

this is likely why Zillion text is in japanese