Add toolbar widget for edit size of handler in diagram editor.

Add a combo box in the tool bar of diagram editor
to quickly change the size of the graphics handler item.

The sarto commit :D

NOTE
only available for diagram editor, element editor will
come later.

sources/qetgraphicsitem/ViewItem/qetgraphicstableitem.cpp

@@ -766,6 +766,7 @@ void QetGraphicsTableItem::hoverEnterEvent(QGraphicsSceneHoverEvent *event)
 	{
 		adjustHandlerPos();
 		this->scene()->addItem(&m_handler_item);
+		m_handler_item.setSize(QETUtils::graphicsHandlerSize(this));
 		m_handler_item.installSceneEventFilter(this);
 	}
 	QGraphicsObject::hoverEnterEvent(event);