add undo command for linkable element

git-svn-id: svn+ssh://svn.tuxfamily.org/svnroot/qet/qet/trunk@2716 bfdf4180-ca20-0410-9c96-a3a8aa849046

sources/qetgraphicsitem/reportelement.cpp

@@ -77,6 +77,17 @@ void ReportElement::unlinkAllElements(){
 		}
 	}
 }
+/**
+ * @brief ReportElement::unlinkElement
+ *unlink the specified element.
+ *for reportelement, they must be only one linked element, so we call
+ *unlinkAllElements for clear the connected_elements list.
+ * @param elmt
+ */
+void ReportElement::unlinkElement(Element *elmt) {
+	Q_UNUSED (elmt);
+	unlinkAllElements();
+}
 
 /**
  * @brief ReportElement::linkType