Limit window size to desktop resolution [Feature Request]

[Formedras]

Please include an option in settings.ini to have the mod detect the desktop resolution and scale the window size down to it. (Probably best for the mod to ignore this option if DisplayMode = 3.)

I play BBTAG on both my laptop's 1080p monitor and a 4K television, and when I switch from one display device to the other, I have to remember to change my window size in settings.ini to adapt. When I have 3840x2160 set and play on the laptop display, I only see a quarter of the screen. When I have 1920x1080 set and play on the television, the full game window only takes up a quarter of the display.

NOTE: The feature can be tested even on just a 1080p monitor if a feature exists on the system to provide a virtual resolution, such as Dynamic Super Resolution on Maxwell (900 series) or newer Geforce cards.