Remove Windows CE support

Windows CE doesn't seem to be supported by Microsoft any longer. Last CE
release was in early 2013 and the PocketPC and Smartphone targets supported by
wxWidgets are long gone.

The build files where already removed in an earlier cleanup this commit
removes all files, every #ifdef and all documentation regarding the Windows CE
support.

Closes https://github.com/wxWidgets/wxWidgets/pull/81

include/wx/msw/notebook.h

@@ -185,15 +185,12 @@ protected:
   bool DoDrawBackground(WXHDC hDC, wxWindow *child = NULL);
 #endif // wxUSE_UXTHEME
 
-  // these function are only used for reducing flicker on notebook resize and
-  // we don't need to do this for WinCE
-#ifndef __WXWINCE__
+  // these function are used for reducing flicker on notebook resize
   void OnEraseBackground(wxEraseEvent& event);
   void OnPaint(wxPaintEvent& event);
 
   // true if we have already subclassed our updown control
   bool m_hasSubclassedUpdown;
-#endif // __WXWINCE__
 
 #if wxUSE_UXTHEME
   // background brush used to paint the tab control