Disassembly does not "respect" MapCtl

Disassembly always shows ROM for $fe00...$feff.

Small change in core.cpp (hack)
```
uint8_t const* Core::debugROM()
{
  if (mMapCtl.romDisable) {
    return &mRAM[0xfe00];
  } else {
    return &mROM[0];
  }
}
```

fixes it.