Add the concept of QNames to elements
Elements can have a namespace prefix mapping
Rewrite string tokenization

This new form is closer to the final NCName and QName parsing that
will need to be done.
Add basic XPath namespace structure
Make finding namespaces const-safe
Add interface to namespace resolving
Accept a PrefixedName in the element test
Add constructor for a prefixed name without a prefix
Add basic tests for the element() node test
Add predicates for the optional components of QNames and PrefixedNames
Do not select elements when they do not have a namespace
Do not select elements when the namespace prefix does not exist
Make QName delegate to PrefixedName
Do not select elements when the namespace does not match the prefix
Return PrefixedName from a token
Make early-return statements less verbose
Add acceptance test for mismatched namespaces
Print the prefixed name when debugging the element() node test