Remove global args from preloader.cpp

This removes all global args from preloader.cpp, and changes all 'dwgfx'
to 'graphics'.

desktop_version/src/main.cpp

@@ -357,7 +357,7 @@ int main(int argc, char *argv[])
             {
             case PRELOADER:
                 //Render
-                preloaderrender(graphics, game, help);
+                preloaderrender();
                 break;
         #if !defined(NO_CUSTOM_LEVELS)
             case EDITORMODE: