* Confirm stopping emulation when the window is closing, not just the "Stop" button
* Don't resume if we were already paused when we got the quit event
* Shutdown the core at the end of main() so we don't crash on exit
* Miscellaneous other logic cleanups related to this
The UI should decide on where it wants the user directory, not our core system.
This is in anticipation of some upcoming work on Android which will need proper user directory setting.
