change a small bit in the way valididy error messages get initialized

* parserInternals.c: change a small bit in the way valididy
  error messages get initialized
* python/TODO python/libxml.c python/libxml2-python-api.xml
  python/libxml2class.txt python/libxml_wrap.h python/types.c:
  added some memory debugging to track leaks at the libxml2 level
* python/tests/*.py: changed all tests to check for leaks,
  there is just one left in XPath extension registrations.
daniel

python/libxml_wrap.h

@@ -35,6 +35,7 @@ typedef struct {
 } PyparserCtxt_Object;
 
 PyObject * libxml_intWrap(int val);
+PyObject * libxml_longWrap(long val);
 PyObject * libxml_xmlCharPtrWrap(xmlChar *str);
 PyObject * libxml_constxmlCharPtrWrap(const xmlChar *str);
 PyObject * libxml_charPtrWrap(char *str);