Merge PyXML 1.11-1.26:

Re-arrange the imports into "Python normal form."
Add test of the getUserData() / setUserData() methods, including the
NODE_CLONED callback.

Added support for renameNode() and getInterface().
Changed Node.unlink() so an unlinked node is not rendered completely
unusable by setting childNodes to None.
Element.removeAttributeNode() is slightly less destructive.

Added test for the wholeText attribute.

Added a test for Text.replaceWholeText().

Fixed to properly create Element in test of user data

Rename a local variable so it makes sense when viewed as a sequence.
Unlink a few documents when we're done with them.

Added tests to define the behavior of the cloneNode() and importNode()
mehods, especially in the "difficult" cases of document and
document-type nodes.

Filled in a few more of the other cloneNode() tests.

NodeList.item() does not exist before Python 2.2, since it requires being
able to create subtypes of list.  Use the subscript syntax instead.

Added a test that minidom documents can be pickled and unpickled.
Closes SF bug #609641.

Fill in an empty test, making sure we get the whitespace right for the
data attribute of a processing instruction.

Added checks for a few more invariants for processing instructions.

testProcessingInstruction():  The length attribute of the NodeList
    interface is not implemented for Python 2.0, 2.1, so only use
    len() to test the length.

testSchemaType():  New test, testing just the minimum of schemaType
    support; this is different from the test_xmlbuilder version of the
    test since it doesn't rely on using a specific builder, and the
    builders support different levels of DTD support.

Add tests for the removeNamedItem() and removeNamedItemNS() methods of
the NamedNodeMap instances found on Element nodes.
These do not pass; the fix will be committed shortly.

Added support for the DOM Level 3 (draft) Element.setIdAttribute*() methods.

Do more to avoid creating new Attr nodes, so that attributes do not lose
their ID-ness when set using setIdAttribute*().