Enhancement: Add an exit button in the main menu to close the game

[JackXson-Real]

Pretty simple, just have an exit button below the credits button in the main menu. I know that in 0.4.1 you can press escape on the title screen to exit, but it would be nice to also have an actual button in the main menu since its one less menu you have to go to, plus there currently is no indicator showing you can press escape to exit the game on the title screen.

[tposejank]

Me when suddenly a new button that interferes with my muscle memory is added and it causes internal rage

[EliteMasterEric]

We might consider this for the future.

[Lasercar]

Is it also going to have an 'are you sure?' thing as well?