Tiny fix to start the game on some systems — IsoMetro Steam update #503425

This update is for Windows users who are experiencing IsoMetro failing to launch. It seems to be a result of telling SDL (the library we use for keyboard, mouse, drawing in the window, etc.) to initialize features we don't even use -- allowing more to go wrong from differences in system configuration. Multiplayer features are around the corner, but this isn't that update. It's still in the works.