Small fixes for Tex2RTF but alas, we still get memory problems.

Added wxUSE_MFC setting (doesn't include windows.h, removes own memory
tracing); added include <ctype.h> in case where PCH isn't used;
wxExit now exits :-)


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@6587 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

utils/tex2rtf/src/texutils.cpp

@@ -1569,7 +1569,8 @@ void Tex2RTFYield(bool force)
     yieldCount = 0;
   if (yieldCount == 0)
   {
-    wxYield();
+    if (wxTheApp)
+        wxYield();
     yieldCount = 10;
   }
   yieldCount --;