Fixed a really nasty problem raised by a DocBook XSLT transform provided

* entities.c parser.c tree.c include/libxml/entities.h: Fixed
  a really nasty problem raised by a DocBook XSLT transform
  provided by Sebastian Bergmann
Daniel
diff --git a/tree.c b/tree.c
index 807189e..67b7d16 100644
--- a/tree.c
+++ b/tree.c
@@ -837,6 +837,7 @@
 
 			    ent->children = xmlStringGetNodeList(doc,
 				    (const xmlChar*)node->content);
+			    ent->owner = 1;
 			    temp = ent->children;
 			    while (temp) {
 				temp->parent = (xmlNodePtr)ent;