Move quit to menu to Game::quittomenu()

I don't want the quit code to only be in the state machine, but I'll
keep the gamestate around for compatibility reasons (there are custom
levels that directly use gamestate 80 to quit to the menu).

desktop_version/src/Game.cpp

@@ -1336,44 +1336,7 @@ void Game::updatestate()
             if(graphics.fademode == 1)	state++;
             break;
         case 81:
-            gamestate = TITLEMODE;
+            quittomenu();
-            graphics.fademode = 4;
-            music.play(6);
-            graphics.backgrounddrawn = false;
-            map.tdrawback = true;
-            graphics.flipmode = false;
-            //Don't be stuck on the summary screen,
-            //or "who do you want to play the level with?"
-            //or "do you want cutscenes?"
-            //or the confirm-load-quicksave menu
-            if (wasintimetrial)
-            {
-                returntomenu(Menu::timetrials);
-            }
-            else if (wasinintermission)
-            {
-                returntomenu(Menu::intermissionmenu);
-            }
-            else if (wasinnodeathmode)
-            {
-                returntomenu(Menu::playmodes);
-            }
-            else if (wasincustommode)
-            {
-                returntomenu(Menu::levellist);
-            }
-            else if (save_exists() || anything_unlocked())
-            {
-                returntomenu(Menu::play);
-            }
-            else
-            {
-                createmenu(Menu::mainmenu);
-            }
-            wasintimetrial = false;
-            wasinintermission = false;
-            wasinnodeathmode = false;
-            wasincustommode = false;
             state = 0;
             break;
 
@@ -7358,3 +7321,45 @@ bool Game::save_exists()
 {
     return telesummary != "" || quicksummary != "";
 }
+
+void Game::quittomenu()
+{
+    gamestate = TITLEMODE;
+    graphics.fademode = 4;
+    music.play(6);
+    graphics.backgrounddrawn = false;
+    map.tdrawback = true;
+    graphics.flipmode = false;
+    //Don't be stuck on the summary screen,
+    //or "who do you want to play the level with?"
+    //or "do you want cutscenes?"
+    //or the confirm-load-quicksave menu
+    if (wasintimetrial)
+    {
+        returntomenu(Menu::timetrials);
+    }
+    else if (wasinintermission)
+    {
+        returntomenu(Menu::intermissionmenu);
+    }
+    else if (wasinnodeathmode)
+    {
+        returntomenu(Menu::playmodes);
+    }
+    else if (wasincustommode)
+    {
+        returntomenu(Menu::levellist);
+    }
+    else if (save_exists() || anything_unlocked())
+    {
+        returntomenu(Menu::play);
+    }
+    else
+    {
+        createmenu(Menu::mainmenu);
+    }
+    wasintimetrial = false;
+    wasinintermission = false;
+    wasinnodeathmode = false;
+    wasincustommode = false;
+}

desktop_version/src/Game.h

@@ -385,6 +385,8 @@ public:
     int playrx;
     int playry;
     int playgc;
+
+    void quittomenu();
 };
 
 extern Game game;