Put screen effects render handling inside a function

This de-duplicates the screen effects rendering code by putting it
inside a function, Graphics::renderwithscreeneffects(), and using that
instead of copy-pasted code.

desktop_version/src/preloader.cpp

@@ -95,17 +95,5 @@ void preloaderrender()
 
   graphics.drawfade();
 
-  if (game.flashlight > 0 && !game.noflashingmode)
-  {
-    graphics.flashlight();
-  }
-
-  if (game.screenshake > 0  && !game.noflashingmode)
-  {
-    graphics.screenshake();
-  }
-  else
-  {
-    graphics.render();
-  }
+  graphics.renderwithscreeneffects();
 }