Include wx/settings.h according to precompiled headers of wx/wx.h (with other minor cleaning).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39310 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/univ/themes/metal.cpp

@@ -46,11 +46,11 @@
         #include "wx/msw/private.h"
     #endif
     #include "wx/menu.h"
+    #include "wx/settings.h"
 #endif // WX_PRECOMP
 
 #include "wx/notebook.h"
 #include "wx/spinbutt.h"
-#include "wx/settings.h"
 #include "wx/artprov.h"
 #include "wx/toplevel.h"