applied patch from Alfred Mickautsch fixing a memory leak reported on the

* xmlwriter.c: applied patch from Alfred Mickautsch fixing a memory
  leak reported on the list.
Daniel
diff --git a/xmlwriter.c b/xmlwriter.c
index 5a31125..720c20d 100644
--- a/xmlwriter.c
+++ b/xmlwriter.c
@@ -65,6 +65,7 @@
     int doindent;	    /* internal indent flag */
     xmlChar *ichar;            /* indent character */
     char qchar;             /* character used for quoting attribute values */
+    xmlParserCtxtPtr ctxt;
 };
 
 static void xmlFreeTextWriterStackEntry(xmlLinkPtr lk);
@@ -249,6 +250,8 @@
         return NULL;
     }
 
+    ret->ctxt = ctxt;
+
     return ret;
 }
 
@@ -373,6 +376,9 @@
     if (writer->nsstack != NULL)
         xmlListDelete(writer->nsstack);
 
+    if (writer->ctxt != NULL)
+        xmlFreeParserCtxt(writer->ctxt);
+
     xmlFree(writer);
 }