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/qetgraphicsitem/qetshapeitem.h

@@ -20,6 +20,9 @@
 
 #include "qetgraphicsitem.h"
 
+class QDomElement;
+class QDomDocument;
+
 /**
  * @brief The QetShapeItem class
  * this class is used to draw a basic shape (line, rectangle, ellipse)