[BUG] Uninitialized variable in XmlMDataStd_NamedDataDriver.cxx

As Pawel noticed in http://www.opencascade.org/org/forum/thread_21388/ this file contains several occurences of this pattern:

LDOM_Element* aCurElement;
if (aCurNode.isNull())
aCurNode = anElement.getFirstChild();
else
aCurNode = aCurElement->getNextSibling();

Of course, aCurElement is uninitialized in the else clause.