Improve build and widget storage

There are no longer any qt headers included in wx/qt headers.
Applications do not need to link with qt librarys anymore, only wxqt libraries.
wxWindow and derived widgets only contain one pointer to their qtwidget, no longer
  carrying both base and derived pointers in parallel as was before.

include/wx/qt/window.h

@@ -9,8 +9,27 @@
 #ifndef _WX_QT_WINDOW_H_
 #define _WX_QT_WINDOW_H_
 
-#include <QtWidgets/QWidget>
-#include <QtWidgets/QScrollArea>
+#include <list>
+
+class QWidget;
+class QScrollWindow;
+class QAbstractScrollArea;
+class QScrollArea;
+class QPicture;
+class QPainter;
+
+class QPaintEvent;
+class QResizeEvent;
+class QWheelEvent;
+class QKeyEvent;
+class QMouseEvent;
+class QEvent;
+class QMoveEvent;
+class QEvent;
+class QEvent;
+class QCloseEvent;
+class QContextMenuEvent;
+class QFocusEvent;
 
 class WXDLLIMPEXP_FWD_CORE wxScrollBar;
 class WXDLLIMPEXP_FWD_CORE wxQtShortcutHandler;
@@ -112,7 +131,7 @@ public:
     virtual bool SetTransparent(wxByte alpha);
     virtual bool CanSetTransparent() { return true; }
 
-    virtual WXWidget GetHandle() const;
+    QWidget *GetHandle() const;
 
     virtual void SetDropTarget( wxDropTarget *dropTarget );
     
@@ -148,7 +167,7 @@ public:
     virtual void QtHandleShortcut ( int command );
 #endif // wxUSE_ACCEL
 
-    virtual QAbstractScrollArea *QtGetScrollBarsContainer() const;
+    virtual QScrollArea *QtGetScrollBarsContainer() const;
 
 protected:
     virtual void DoGetTextExtent(const wxString& string,
@@ -206,7 +225,7 @@ private:
     bool m_mouseInside;
 
 #if wxUSE_ACCEL
-    QList< QShortcut* > m_qtShortcuts;
+    QList< QShortcut* > *m_qtShortcuts;
     wxQtShortcutHandler *m_qtShortcutHandler;
     bool m_processingShortcut;
 #endif // wxUSE_ACCEL