Remove simple keyboard model

Remove the FLTK simple keyboard system and reorganise things in
preparation for a more direct approach.
diff --git a/vncviewer/Viewport.h b/vncviewer/Viewport.h
index 0523cd1..d9eea35 100644
--- a/vncviewer/Viewport.h
+++ b/vncviewer/Viewport.h
@@ -70,8 +70,11 @@
   void handlePointerEvent(const rfb::Point& pos, int buttonMask);
   static void handlePointerTimeout(void *data);
 
-  rdr::U32 translateKeyEvent(int keyCode, int origKeyCode, const char *keyText);
-  void handleKeyEvent(int keyCode, int origKeyCode, const char *keyText, bool down);
+  void handleKeyPress(int keyCode, rdr::U32 keySym);
+  void handleKeyRelease(int keyCode);
+
+  rdr::U32 translateKeyEvent(void);
+  void handleFLTKKeyPress(void);
 
   void initContextMenu();
   void popupContextMenu();
@@ -91,6 +94,7 @@
   typedef std::map<int, rdr::U32> DownMap;
   DownMap downKeySym;
 
+  rdr::U32 menuKeySym;
   int menuKeyCode;
   Fl_Menu_Button *contextMenu;