per game settings

first draft, there's still some things I'm unsure about and this definitely needs testing (I barely tested any of the options and just acted like if one works, all work).

obvious points of discussion:

* which settings should be per game
* try to load game config in both "EmuScreen::bootGame" and "Load_PSP_ISO" ?
* what to do to not use `NativeMessageReceived("stop","");` but also unload the config with the windows menu via "Emulation->stop"