learning to cope with expat to populate namespace
added NodeSet2 files
gave up with the hashtable, the xml uses 62541-datatype-names only for
the second level elements but attribute names on the third and
following.
coming closer.
relocated xml2ns0.c to examples/src
some refactorings, still open: how and when to inform parent
happy-path is working :-)
added insert to namespace + small bugfixes
Merge pull request #56 from uleon/master

Sketch of solution to #54