Remove unused variable Game::sfpsmode

This variable does absolutely nothing, so I'm removing it.

desktop_version/src/Game.cpp

@@ -268,7 +268,6 @@ void Game::init(void)
     hardestroomdeaths = 0;
     currentroomdeaths=0;
 
-    sfpsmode = false; //by default, play at 30 fps
     inertia = 1.1f;
     swnmode = false;
     swntimer = 0;

desktop_version/src/Game.h

@@ -170,9 +170,6 @@ public:
     int creditposx, creditposy, creditposdelay;
 
 
-    //60 fps mode!
-    bool sfpsmode;
-
     //Sine Wave Ninja Minigame
     bool swnmode;
     int swngame, swnstate, swnstate2, swnstate3, swnstate4, swndelay, swndeaths;