Xml Validation Interoperability Framework

The xvif syntax has been cleaned up to play better with Relax NG as
its host language, and the implementation of W3C XML Schema simple
datatypes has been started. The online validator has also been
improved to browse the test cases, and cross links have been added
between the validator, the test cases, and the strawman.

Even though this is not a major release, a couple of bugs related to the core
Relax NG datatypes have been fixed and the opportunity has been taken to add a
basic yet general mechanism to plug in datatype libraries. The only datatype
library which is implemented is the core type library of Relax NG. That doesn't
change a lot for the users, but this is still an important step toward full
support of type libraries.

This release has a package of the Relax NG test suites (official and specific) and a bugfix (bug 20: false detection of forbidden recursions).

A generic test suite has been set up for transformations. xmlcomp, a simple and flexible XML comparison tool, has been created. In this release, the test suite has been applied to the Regular Fragmentations implementation, and might be used for other transformations in future versions. Xmlcomp has been designed with the ability to define what needs to be tested and may ignore "details" such as namespace prefixes, whitespaces, empty text nodes, namespace declarations, etc.