Add wxKeyEvent::IsAutoRepeat()

The new method is currently supported in Qt, Cocoa, MSW ports (i.e. all
major ones except for wxGTK).

Keyboard example updated with a "Repeat" column.

Closes https://github.com/wxWidgets/wxWidgets/pull/2414

samples/keyboard/keyboard.cpp

@@ -235,7 +235,7 @@ MyFrame::MyFrame(const wxString& title)
                                             wxTE_READONLY);
     headerText->SetValue(
                " event          key     KeyCode mod   UnicodeKey  "
-               "  RawKeyCode RawKeyFlags  Position");
+               "  RawKeyCode RawKeyFlags  Position      Repeat");
 
 
     m_logText = new wxTextCtrl(this, wxID_ANY, "",
@@ -538,6 +538,7 @@ void MyFrame::LogEvent(const wxString& name, wxKeyEvent& event)
                    "  not-set    not-set"
 #endif
                    "  (%5d,%5d)"
+                   "  %s"
                    "\n",
                name,
                GetKeyName(event),
@@ -556,6 +557,7 @@ void MyFrame::LogEvent(const wxString& name, wxKeyEvent& event)
 #endif
                , event.GetX()
                , event.GetY()
+               , event.IsAutoRepeat() ? "Yes" : "No"
                );
 
     m_logText->AppendText(msg);