[xml] Namespace declaration serialization

[Anthony Carrico <acarrico memebeam org>]

Namespace declaration serialization seems broken, or absent. For
example:

$ cat tmp2.py

import libxml2
try:
    doc = libxml2.newDoc("1.0")
    e = doc.newChild(None, "test", None)
    nsd = e.newNs("http://bogus";, "prefix")
    print
    print "element: " + repr(e)
    print "element serialization: " + repr(e.serialize())
    print "namespace declaration: " + repr(nsd)
    print ("namespace declaration serialization: "
           + repr(nsd.serialize()))
    print
finally:
    if doc: doc.freeDoc()

$ python tmp2.py

element: <xmlNode (test) object at 0x4076b0cc>
element serialization: '<test xmlns:prefix="http://bogus"/>'
namespace declaration: <xmlNs (prefix) object at 0x406d44ac>
namespace declaration serialization: None

--
Anthony Carrico