Add being able to toggle over/fixed-30-FPS, off by default

There is now an option in "graphic options" named "toggle fps", which
toggles whether the game visually runs at 1000/34 FPS or over 1000/34
FPS. It is off by default.

I've had to put the entire game loop in yet another set of braces, I'll
indent it next commit.

desktop_version/src/Input.cpp

@@ -358,6 +358,12 @@ void menuactionpress()
                 graphics.showmousecursor = true;
             }
             break;
+        case 5:
+            //toggle 30+ fps
+            music.playef(11);
+            game.over30mode = !game.over30mode;
+            game.savestats();
+            break;
         default:
             //back
             music.playef(11);