Basic support for QEMU Extended Key Events

This adds the basic infrastructure and handshake for the QEMU
Extended Key Events extension. No viewer or server makes use of
the extra functionality yet though.
diff --git a/win/rfb_win32/SInput.h b/win/rfb_win32/SInput.h
index 2a0b3e6..f7949ec 100644
--- a/win/rfb_win32/SInput.h
+++ b/win/rfb_win32/SInput.h
@@ -53,7 +53,7 @@
     class SKeyboard {
     public:
       SKeyboard();
-      void keyEvent(rdr::U32 key, bool down);
+      void keyEvent(rdr::U32 keysym, rdr::U32 keycode, bool down);
       static BoolParameter deadKeyAware;
     private:
       std::map<rdr::U32,rdr::U8> vkMap;