Merge branch 'prewinxp_cleanup' of https://github.com/TcT2k/wxWidgets

Remove the code checking for Windows versions < XP and update the documention
to not mention them any more neither.

Closes https://github.com/wxWidgets/wxWidgets/pull/82

include/wx/msw/app.h

@@ -102,10 +102,6 @@ public:
     // wasn't found at all
     static int GetComCtl32Version();
 
-    // the same for shell32.dll: returns 400, 471, 500, 600, ... (4.70 not
-    // currently detected)
-    static int GetShell32Version();
-
     // the SW_XXX value to be used for the frames opened by the application
     // (currently seems unused which is a bug -- TODO)
     static int m_nCmdShow;