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/apptrait.h

@@ -28,10 +28,8 @@ public:
     virtual bool DoMessageFromThreadWait();
     virtual WXDWORD WaitForThread(WXHANDLE hThread, int flags);
 #endif // wxUSE_THREADS
-#ifndef __WXWINCE__
     virtual bool CanUseStderr() { return true; }
     virtual bool WriteToStderr(const wxString& text);
-#endif // !__WXWINCE__
 };
 
 #if wxUSE_GUI
@@ -53,10 +51,8 @@ public:
 #endif // wxUSE_THREADS
     virtual wxPortId GetToolkitVersion(int *majVer = NULL, int *minVer = NULL) const;
 
-#ifndef __WXWINCE__
     virtual bool CanUseStderr();
     virtual bool WriteToStderr(const wxString& text);
-#endif // !__WXWINCE__
 };
 
 #elif defined(__WXGTK__)
@@ -83,10 +79,8 @@ public:
 #endif // wxUSE_THREADS
     virtual wxPortId GetToolkitVersion(int *majVer = NULL, int *minVer = NULL) const;
 
-#ifndef __WXWINCE__
     virtual bool CanUseStderr() { return false; }
     virtual bool WriteToStderr(const wxString& WXUNUSED(text)) { return false; }
-#endif // !__WXWINCE__
 };
 
 #endif