applied patch from Brent Hendricks adding namespace removal at the python

* python/libxml.c python/libxml.py: applied patch from Brent Hendricks
  adding namespace removal at the python level #300209
* python/tests/Makefile.am python/tests/nsdel.py: added the regression
  test
Daniel

python/tests/nsdel.py

@@ -0,0 +1,62 @@
+#!/usr/bin/python -u
+#
+# this test exercise the XPath basic engine, parser, etc, and
+# allows to detect memory leaks
+#
+import sys
+import libxml2
+
+instance="""<?xml version="1.0"?>
+<tag xmlns:foo='urn:foo' xmlns:bar='urn:bar' xmlns:baz='urn:baz' />"""
+
+def namespaceDefs(node):
+    n = node.nsDefs()
+    while n:
+        yield n
+        n = n.next
+
+def checkNamespaceDefs(node, count):
+    nsList = list(namespaceDefs(node))
+    #print nsList
+    if len(nsList) != count :
+        raise Exception, "Error: saw %d namespace declarations.  Expected %d" % (len(nsList), count)
+    
+# Memory debug specific
+libxml2.debugMemory(1)
+
+# Remove single namespace
+doc = libxml2.parseDoc(instance)
+node = doc.getRootElement()
+checkNamespaceDefs(node, 3)
+ns = node.removeNsDef('urn:bar')
+checkNamespaceDefs(node, 2)
+ns.freeNsList()
+doc.freeDoc()
+
+# Remove all namespaces
+doc = libxml2.parseDoc(instance)
+node = doc.getRootElement()
+checkNamespaceDefs(node, 3)
+ns = node.removeNsDef(None)
+checkNamespaceDefs(node, 0)
+ns.freeNsList()
+doc.freeDoc()
+
+# Remove a namespace refered to by a child
+doc = libxml2.newDoc("1.0")
+root = doc.newChild(None, "root", None)
+namespace = root.newNs("http://example.com/sample", "s")
+child = root.newChild(namespace, "child", None)
+root.removeNsDef("http://example.com/sample")
+doc.reconciliateNs(root)
+namespace.freeNsList()
+doc.serialize() # This should not segfault
+doc.freeDoc()
+
+# Memory debug specific
+libxml2.cleanupParser()
+if libxml2.debugMemory(1) == 0:
+    print "OK"
+else:
+    print "Memory leak %d bytes" % (libxml2.debugMemory(1))
+    libxml2.dumpMemory()