Fixed|ClientApp: Subsystem deletion order

When the appearance editor is open, the window system is dependent
on the settings in the render subsystem (ClientWindow owns the
sidebar widget).

Todo: Observers should support automatically leaving destroyed
audiences.

doomsday/client/src/clientapp.cpp

@@ -126,8 +126,8 @@ DENG2_PIMPL(ClientApp)
     QMenuBar *menuBar;
     InputSystem *inputSys;
     QScopedPointer<WidgetActions> widgetActions;
-    WindowSystem *winSys;
     RenderSystem *renderSys;
+    WindowSystem *winSys;
     ServerLink *svLink;
     GLShaderBank shaderBank;
     Games games;
@@ -150,8 +150,8 @@ DENG2_PIMPL(ClientApp)
         DD_Shutdown();
 
         delete svLink;
-        delete renderSys;
         delete winSys;
+        delete renderSys;
         delete inputSys;
         delete menuBar;
         clientAppSingleton = 0;