Gracefully close the app on exit (#12)

* Gracefully close the app on exit

* Application tear down

instead of calling Environment.Exit(0); do a better tear down of the application

Program.cs

@@ -50,6 +50,10 @@ namespace Ryujinx
 
             using (GLScreen Screen = new GLScreen(Ns, Renderer))
             {
+                Ns.Finish += (Sender, Args) => {
+                    Screen.Exit();
+                };
+
                 Screen.Run(60.0);
             }