centralized Esc key handling for closing the dialogs in wxDialogBase:

1. added wxDialogBase::OnCharHook() and removed this event handler from
   all the other ports
2. also removed ad hoc code doing the same thing in wxMSW (MSWProcessMessage()
   override in wxDialog) and wxGTK (in gtk_window_key_press_callback())
3. reimplemented EmulateButtonClickIfPresent() portably and also moved it
   to wxDialogBase from wxMSW wxDialog


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@40686 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/dialog.h

@@ -52,9 +52,6 @@ public:
     void OnOK( wxCommandEvent &event );
     void OnPaint( wxPaintEvent& event );
     void OnCloseWindow( wxCloseEvent& event );
-    /*
-       void OnCharHook( wxKeyEvent& event );
-     */
 
     virtual bool Show( bool show = TRUE );
     virtual int ShowModal();