applied patch from Stéphane Bidoul to fix some Python bindings

* python/libxml.c python/generator.py python/libxml.py
  python/libxml2-python-api.xml python/libxml2class.txt:
  applied patch from Stéphane Bidoul to fix some Python bindings
  initialization, then had to change the parserCleanup()
  to handle memory released there.
* xmlmemory.c: added more debugging comments.
Daniel
diff --git a/python/libxml2class.txt b/python/libxml2class.txt
index 7479843..6266a9d 100644
--- a/python/libxml2class.txt
+++ b/python/libxml2class.txt
@@ -104,7 +104,6 @@
 nanoHTTPScanProxy()
 
 # functions from module parser
-cleanupParser()
 createDocParserCtxt()
 initParser()
 keepBlanksDefault()
@@ -151,6 +150,7 @@
 htmlCreatePushParser()
 htmlSAXParseFile()
 newNode()
+pythonCleanupParser()
 setEntityLoader()
 
 # functions from module relaxng