#186 Retina support

[Madd the Sane]

As it is, Hexen 2 doesn't like my Mac with a built-in Retina display. First, it tries to fill the screen with a window that is double the size of the actual screen. If I set the display manually, (-width 800 -height 600 -bpp 32) the actual screen is in the lower left-hand corner of the screen (see attachment).