Remove retro compatibility of element text item prior to qet 0.7

Compatibility is not maintained anymore with the old project which
contain old element text item.

sources/qetgraphicsitem/element.h

@@ -202,18 +202,6 @@ class Element : public QetGraphicsItem
 		void hoverLeaveEvent(QGraphicsSceneHoverEvent *) override;
 
 	protected:
-		// m_converted_text_from_description,
-		// when a element is created from his description,
-		// the old element text item (tagged as 'input' in the xml)
-		// are converted to dynamic text field,
-		// the QPointF is the original position of the text item,
-		// because the origin transformation point of text item
-		// and dynamic text item are not the same,
-		// so we must to keep a track of this value,
-		// to be use in the function element::fromXml
-		QHash <DynamicElementTextItem *, QPointF>
-		m_converted_text_from_xml_description;
-
 			//ATTRIBUTES related to linked element
 		QList <Element *> connected_elements;
 		QList <QUuid>     tmp_uuids_link;