Implement wxGestureEvent support for wxQt

Do it generically in wxWindow and also provide a special version for
wxGLCanvas for which the standard implementation doesn't work well.

include/wx/qt/window.h

@@ -221,6 +221,7 @@ protected:
     // itself.
     virtual QWidget* QtGetParentWidget() const { return GetHandle(); }
 
+    virtual bool EnableTouchEvents(int eventsMask) wxOVERRIDE;
 
     QWidget *m_qtWindow;