Improvement: Use anticipate class declaration instead of include header

git-svn-id: svn+ssh://svn.tuxfamily.org/svnroot/qet/qet/trunk@3224 bfdf4180-ca20-0410-9c96-a3a8aa849046

sources/ui/elementselectorwidget.h

@@ -19,7 +19,8 @@
 #define ELEMENTSELECTORWIDGET_H
 
 #include <QWidget>
-#include "qetgraphicsitem/element.h"
+class Element;
+class QSignalMapper;
 
 namespace Ui {
 	class ElementSelectorWidget;