Initial stab at adding support for SaxonEE


The following takes an initial stab at adding support for SaxonEE.  Had to upgrade the api-validator component as well because of the class loader issue.

Haven't had a chance to add tests so consider this WIP, but have tested manually and SaxonEE features like XSLT 3.0 support work.

You must set "use-saxon" to true on the config for the feature to take effect.  If use-saxon is false (or not specified) we revert back to using open source saxon -- without the EE features.

One issue with testing is that we don't want to require a saxon license to run tests.  In the API checker lib -- we have a sperate profile that runs saxon specific tests so that's something we could try.