Merge pull request #867 from shimitei/feature/refactor_bg_menu

[Refactor] 壁紙メニューを別階層に分ける

diff --cc src/main-win.cpp
index 45f6110,342f04f..469be75
--- 1/src/main-win.cpp
--- 2/src/main-win.cpp
+++ b/src/main-win.cpp
@@@ -3011,11 -3036,13 +3036,8 @@@ int WINAPI WinMain(_In_ HINSTANCE hInst
      }
  
      init_windows();
-     if (use_bg) {
-         init_background();
-         use_bg = init_bg();
-     }
+     change_bg_mode(current_bg_mode, true);
  
 -    use_music = arg_music;
 -    if (use_music) {
 -        init_music();
 -    }
 -
      plog_aux = hook_plog;
      quit_aux = hook_quit;
      core_aux = hook_quit;