Sandbox mode support

[KiwiHawk]

https://mods.factorio.com/mod/bobclasses/discussion/69a9d36c5b75a8625101d945

As stated in the thread title, it would be cool to support sandbox mode. Basically, in the mod settings, in the map settings, there's an option to display the God Mode button, but your God Mode inventory will be permanently deleted when switching to your avatar and back, as if you'd never been in God Mode. And this button should be enabled by default if the map started in Sandbox mode.
Overall, this is a cool mod for players like me who sometimes enjoy playing in Sandbox mode with extreme difficulty settings. This mod helps solve certain situations where you want to leave Sandbox mode, arm yourself with a ton of weapons, and beat up the Bitters with your own hands, rather than with a turret creep.

[Qatavin]

Sounds like the thing to do is save the god-controller's inventory in a variable table when you switch out of it.

I'm not sure if having the button enabled when you start the game in Sandbox mode is possible, though. Maybe we could set things up so that the button will always be there if you begin the game controlling a god-controller?