Add "Auto Zen mode" setting

[yanzay]

Add setting "Auto Zen mode" and go to Zen mode automatically when joining the game:

[honganhkhoa]

The commit looks good, but the way this feature is implemented feels off to me: if someone wants to use Zen mode everytime, instead of having to activate Zen mode every time, now they have to deactivate it every time in order to exit the view.

I think a better way to implement this would be to add a "Back" button to the Zen mode view, and if someone exits the view with that button (without deactivating Zen mode) then it automatically opens game with Zen mode next time. That way we can also avoid adding another setting (I have been trying to avoid having too many settings).

Is it your personal preference to always play with Zen mode? Let me know what you think.

Thanks.

[honganhkhoa]

if someone wants to use Zen mode everytime, instead of having to activate Zen mode every time, now they have to deactivate it every time in order to exit the view.

Sorry this is inaccurate, because as it is now we still have to deactivate Zen mode every time. Still, I think it's better if we can implement it in a way that can remove the need of both activating and deactivating Zen mode if possible.