cleanup the extension function lookup always compile the list Daniel

* python/TODO python/libxml.c: cleanup the extension function lookup
* xmlmemory.c include/libxml/xmlmemory.h: always compile the list
Daniel
diff --git a/python/TODO b/python/TODO
index a19dfe4..f446f6e 100644
--- a/python/TODO
+++ b/python/TODO
@@ -13,6 +13,8 @@
 - access to XPath variables
 - xmlBuffer exposure
 - xpathContext, being able to set/get info and clean it up
+- more work needed on context handling for function lookup
+  and use of an hash table.
 - add regression tests
    - SAX flow
 - DTD element and attributes content accesses