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/accel.h

@@ -9,9 +9,6 @@
 #ifndef _WX_QT_ACCEL_H_
 #define _WX_QT_ACCEL_H_
 
-#include <QtCore/QList>
-#include <QtWidgets/QShortcut>
-
 /* wxQt accelerators implementation:
  *
  * Storing:
@@ -36,6 +33,9 @@
  * QShortcut. This handler will finally create and send the appropriate wx
  * event to the window. */
 
+class QShortcut;
+template < class T > class QList;
+
 class WXDLLIMPEXP_CORE wxAcceleratorTable : public wxObject
 {
 public:
@@ -43,7 +43,7 @@ public:
     wxAcceleratorTable(int n, const wxAcceleratorEntry entries[]);
 
     // Implementation
-    QList< QShortcut* > ConvertShortcutTable( QWidget *parent ) const;
+    QList < QShortcut* > *ConvertShortcutTable( QWidget *parent ) const;
 
     bool Ok() const { return IsOk(); }
     bool IsOk() const;